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The new resistance jump: The detection of damage in Nb barrier in MgB2 wires
Materials Letters 160 (2015) 81–84
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
The new resistance jump: The detection of damage in Nb barrier in MgB2 wires Daniel Gajda a,n, Andrzej Morawski b, Andrzej Janusz Zaleski c, Matthew A. Rindfleisch d, Chee Thong d, Michael Tomsic d, Md Shahriar Hossain e,n, Tomasz Cetner b a
International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, 53-421 Wroclaw, Poland Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warszawa, Poland c Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wroclaw, Poland d Hyper Tech Research, Inc., 539 Industrial Mile Rd, Columbus, OH 43228, USA e Institute for Superconducting and Electronic Materials, AIIM, University of Wollongong, North Wollongong, NSW 2519, Australia b
art ic l e i nf o
a b s t r a c t
Article history: Received 8 June 2015 Received in revised form 9 July 2015 Accepted 15 July 2015 Available online 17 July 2015
We present a new method for detecting damage to Nb barriers in MgB2 wires by using a four-contact probe. The transport measurements and scanning electron microscope images indicate that a newly identified jump in resistance means that there is damage to the Nb barrier. Damage detection is important for application because it allows us to avoid reactions between the filament and the sheath material, and to develop implementation methods for MgB2 with high critical current density. Our methods for damage detection proposed in this paper are simple, fast, and easy to use. & 2015 Published by Elsevier B.V.
Keywords: Magnesium diboride Damage detection Critical current
1. Introduction The superconductivity at high critical temperature (39 K) of cheap MgB2 material was discovered in 2001 by Akimitsu's group [1,2]. Various studies have shown that doping with SiC, C, and multi-walled carbon nanotubes promotes an increased irreversibility field (Birr) and increased critical current density (Jc) in high magnetic fields [3–7]. Furthermore, the high critical temperature (Tc) of MgB2 allows us to cool MgB2 wires by cryocooler, with no need to use expensive liquid helium. Pure Mg is a highly reactive material [8]. Its application in MgB2 wires requires barrier materials, which eliminate the reaction of Mg with the wire sheath [9– 11]. Although Nb is a widely used barrier material in MgB2 wires, breakage of the Nb during the wire drawing is a problem [12–14]. This damage causes the Mg to react with the wire shielding and reduces the amount of superconducting material in the filament. It also reduces the current carrying capability in MgB2 wires. In this article, we present a new method for detecting damage in Nb n
Corresponding authors. E-mail addresses: [email protected] (D. Gajda), [email protected] (M.S. Hossain). http://dx.doi.org/10.1016/j.matlet.2015.07.076 0167-577X/& 2015 Published by Elsevier B.V.
barriers. There is currently no information on any method that can detect such damage in the barriers of MgB2 wires. The lack of such a method significantly impedes research that is aimed at improving the superconducting and electrical properties in MgB2 wires. Two MgB2 wires with Nb barriers were made by Hyper Tech Research, Inc., using the powder-in-tube (PIT) method. The methods for producing wires and components of MgB2 materials are described in previous articles [14–16]. The samples were annealed at 700 °C in argon gas under isostatic pressure for 15 min at the Institute of High Pressure Physics laboratory (Table 1) [17]. Transport (15 Hz and AC current, IAC ¼260 mA) and magnetic (50 mT) measurements were performed using a physical properties measurement system (PPMS Model 7100, Quantum Design,) in the International Laboratory of High Magnetic Fields and Low Temperature [18]. The samples for transport measurements had a length of 12 mm. X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images were collected at the Institute of Low Temperature and Structure Research, Polish Academy of Sciences (PAS). The powder XRD pattern and elemental maps of undamaged MgB2 samples (insets) are shown in Fig. 1(a), demonstrating the lack of any detectable impurity phases in the MgB2 samples, apart
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D. Gajda et al. / Materials Letters 160 (2015) 81–84
Table 1 Technical parameters of MgB2 wires. Sample
Barrier
Mg:B
Sheath
Number of filaments/ fill factor
Diameter (mm)
A1 (damaged) A2 B1 (damaged) B2
Nb Nb Nb Nb
1.1: 1.1: 1.1: 1.1:
Monel Monel Copper Copper
18/15% 18/15% 6/19.4% 6/19.4%
0.83 0.83 0.83 0.83
2 2 2 2
Fig. 1. (a) XRD pattern of MgB2 powder extracted from wire and cross-sectional SEM images of samples (b) A1 and (c) B1. The insets of (a) are cross-sectional elemental mappings of the undamaged samples A2 (left) and B2 (right). The yellow circles in (b) and (c) indicate damage to the Nb barrier. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
from minor traces of MgO. Our SEM studies indicate that the problem of breakage in the Nb barriers in in-situ MgB2 wires. Samples A1 and B1 were cut to include the points in the wires where jump resistance at low temperature was observed, while Samples A2 and B2 were cut from sections of the same respective wires where jump resistance could not be observed. Cross-sectional SEM images of the MgB2 samples featuring the jump resistance show cracks in the Nb barrier (Fig. 1(b and c)). These
images demonstrate that the damage in the Nb barrier creates intermetallic phases outside the superconducting filaments (yellow circles in Fig. 1(b and c)). These phases contain Cu and Mg [19], because the matrix of the wires is made of copper and may create higher non-superconducting borides inside the filament to block the current [20]. Figs. 2(a) and 3(a) show the jumps in the resistance of the samples for which the SEM images reveal damage to the Nb bar-
D. Gajda et al. / Materials Letters 160 (2015) 81–84
83
Fig. 2. Transport R T (IAC ¼ 260 mA) curves for Samples A1 and A2 with Nb barriers: (a) in self-field and low magnetic fields, (b) in high magnetic fields, (c) at temperatures from 45 to 300 K (normal state). (d) Transport B T curves for samples A1 and A2, comparing the critical parameters of the corresponding samples with a damaged and a good Nb barrier.
rier of a filament (Fig. 1). The resistance jumps can be seen within the temperature range from 7.5 K to 10 K. These temperatures are similar to the critical temperature of Nb [21]. Such jumps were not reported in earlier articles. Moreover, in magnetic fields above 1 T, we do not see such jumps. This factor indicates that the jumps are associated with the Nb barrier, because the upper critical field (Bc2) of Nb is about 1 T [21]. In samples with good Nb barriers, we do not see any resistance jumps (Fig. 2(a–b) and Fig. 3(a–b)), and the transition from the superconducting state to the normal state is narrow. The measurements in Fig. 2(c) and Fig. 3(c) indicate that at temperatures from 45 K to 300 K, there is no obvious difference between the samples with good Nb barriers and the ones cut from the same wires with damaged Nb barriers. The value of the critical temperature is determined on the basis of the 50% criterion [22]. The results in Fig. 2(a–b) and Fig. 3(a–b) show that the values of Tc in samples with good barriers and samples with damaged Nb barriers are similar. The values of Birr and Bc2 have been determined with the criterion of 5% and 90%, respectively [22]. The Bc2 in samples with good barriers and samples with damaged barriers is similar, although a significant decrease in Birr can be seen in Sample A1 with a damaged barrier in comparison to Sample A2 with a good barrier. In a 3 T magnetic field, Sample A2 with a good barrier has a Birr that is higher by about 20% than that of the corresponding Sample A1 with a damaged barrier, and it is higher by 40% at 5 T and 60% at 7 T. In the undamaged sample B2, the Birr is higher than Birr in the corresponding damaged sample B1, e.g. at 3 T by about 15%, at 5 T by about 20%, and at 7 T by about 30–40%. In addition, we measured the critical current for samples
with good and damaged barriers and calculated the magnetic critical current density (Jcm) from the Bean model [23]. These results indicate that damage to the Nb barrier reduced Jcm by 5–15%. The transport critical current (Itc) was determined on the basis of the 1 μV/cm criterion [24]. The samples with good barriers have higher Itc than the samples with damaged barriers. Sample A2 (good barrier) has higher Itc by about 15–20% than Sample A1 (damaged barrier), while Sample B2 (good) has higher Itc by about 50% in comparison to Sample B1 (damaged). Our research has demonstrated that the sweep temperature method can detect damage to the Nb barrier. Based on these results, a damaged Nb barrier does not decrease Tc or Bc2, but does decrease Birr and Itc. We suppose that the jump resistance at low temperature (B ¼0 T) can reflect a number of factors, including vortex motion in the barrier, as well as the penetration of the current into the superconducting material through the wire shield and the damaged area. Damage to the barrier causes a significant reduction in the transport parameters, and this may be solved by increasing the thickness of the barriers. These results can be helpful not only for MgB2 wires, but also for detecting damage in any other low- or high-temperature superconductor. Moreover, these results may be the basis for developing an industrial method for detecting damage in MgB2 wires, which would make it possible to reliably obtain MgB2 wires with high Itc.
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D. Gajda et al. / Materials Letters 160 (2015) 81–84
Fig. 3. Transport R T (IAC ¼ 260 mA) curves at 0T for samples B1 and B2 with Nb barriers: (a) in self-field and low magnetic fields, (b) in high magnetic fields, (c) at temperatures from 45 to 300 K (normal state). (d) Transport B T curves for samples B1 and B2, comparing the critical parameters of the corresponding samples with a damaged and good Nb barrier.
Acknowledgments This work was supported by the Institute of High Pressure Physics, PAS and the International Laboratory of High Magnetic Fields and Low Temperatures. It was also partially supported by the Australian Research Council (Grant no. DE130101247), and University of Wollongong and Australian Institute for Innovative Materials (AIIM) internal grants. The authors would like to thank Dr. Tania Silver for critical reading of this manuscript.
References [1] J. Nagamatsu, N. Nakagawa, T. Muranaka, Y. Zenitani, J. Akimitsu, Nature 410 (2001) 63–64. [2] Y. Takano, H. Takeya, H. Furii, H. Kumakura, T. Hatano, K. Toganok, H. Kito, H. Ihara, Appl. Phys. Lett. 78 (2001) 2914. [3] W. Haßler, M. Herrmann, C. Rodig, M. Schubert, K. Nenkov, B. Holzapfel, Supercond. Sci. Technol. 21 (2008) 062001. [4] W.X. Li, R. Zeng, J.L. Wang, Y. Li, S.X. Dou, J. Appl. Phys. 111 (2012) 07E135. [5] D. Patel, M. Maeda, S. Choi, S.J. Kim, M. Shahabuddin, J.M. Parakandy, M.S. A. Hossain, J.H. Kim, Scr. Mater. 88 (2014) 13–16. [6] Z. Ma, Y. Liu, W. Hu, Z. Gao, L. Yu, Z. Dong, Scr. Mater. 61 (2009) 836–839. [7] S. Barua, M.S.A. Hossain, Z. Ma, D. Patel, M. Mustapic, M. Somer, S. Acar, I. Kokal, A. Morawski, T. Cetner, D. Gajda, S.X. Dou, Scr. Mater. 104 (2015) 37–40. [8] J.L. Pelissier, Phys. Scr. 34 (1986) 838. [9] M.A. Susner, T.W. Daniels, M.D. Sumption, M.A. Rindfleisch, C.J. Thong, E. W. Collins, Supercond. Sci. Technol. 25 (2012) 065002. [10] K. Togano, J.M. Hur, A. Matsumoto, H. Kumakura, Supercond. Sci. Technol. 22
(2009) 015003. [11] A. Kario, A. Morawski, B.A. Glowacki, T. Lada, M. Smaga, R. Diduszko, D. Kolesnikov, A.J. Zaleski, A. Kondrat, D. Gajda, Acta Phys. Pol. A 111 (2007) 693. [12] T. Cetner, A. Morawski A, K. Adamczyk, M. Rindfleisch, M. Tomsic, A. Zaleski, D. Gajda, A. Presz, High Press. Res. 32 (2012) 419. [13] G. Aldica, I. Tiseanu, P. Badica, T. Craciunescu, M.A. Rindfleisch, in: A.M. Luiz (Ed.), Chapter 11 in Superconductor, Sciyo, Rijeka, 2010. 14 M. Tomsic, M. Rindfleisch, J. Yue, K. McFadden, J. Phillips, M.D. Sumption, M. Bhatia, S. Bohnenstiehl, E.W. Collings, Int. J. Appl. Ceram. Technol. 4 (2007) 250. [15] M.A. Susner, Y. Yang, M.D. Sumption, E.W. Collings, M.A. Rindfleisch, M. J. Tomsic, J.M. Marzik, Supercond. Sci. Technol. 24 (2011) 012001. [16] M.S.A. Hossain, C. Senatore, M.A. Rindfleisch, R. Flukiger, Supercond. Sci. Technol. 24 (2011) 075013. [17] A. Morawski, T. Łada, K. Przybylski, Physica C 387 (2003) 143. [18] D. Gajda, A. Morawski, A.J. Zaleski, W. Haßler, K. Nenkov, M.A. Rindfleisch, E. Zuchowska, G. Gajda, T. Czujko, T. Cetner, M.S.A. Hossain, J. Appl. Phys. 117 (2015) 173908. [19] M. Woźniak, K.L. Juda, S.C. Hopkins, D. Gajda, B.A. Glowacki, Supercond. Sci. Technol. 26 (2013) 105008. [20] T. Prikhna, M. Eisterer, W. Gawalek, A. Kozyrev, H.W. Weber, V. Sokolovsky, X. Chaud, J. Noudem, T. Habisreuther, V. Moshchil, M. Karpets, T. Basyuk, V. Kovylaev, J. Dellith, V. Sverdun, R. Kuznietsov, C. Shmidt, T. Vitovetskaya, L. Polikarpova, J. Supercond. Novel Magn. 26 (2013) 1569. [21] J.D. McCambridge, The Superconducting Properties of Niobium–Titanium Alloy Multilayers, Yale University thesis (Doctor of Philosophy), 1995. [22] G.Z. Li, Y. Yang, M.A. Susner, M.D. Sumption, E.W. Collings, Supercond. Sci. Technol. 25 (2012) 025001. [23] J. Horvat, W.K. Yeoh, J.H. Kim, S.X. Dou, Supercond. Sci. Technol. 21 (2008) 065003. [24] J.W. Ekin, Experimental Techniques for Low-Temperature Measurements, Oxford University Press, Oxford, 2006.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
The new resistance jump: The detection of damage in Nb barrier in MgB2 wires Daniel Gajda a,n, Andrzej Morawski b, Andrzej Janusz Zaleski c, Matthew A. Rindfleisch d, Chee Thong d, Michael Tomsic d, Md Shahriar Hossain e,n, Tomasz Cetner b a
International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, 53-421 Wroclaw, Poland Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warszawa, Poland c Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wroclaw, Poland d Hyper Tech Research, Inc., 539 Industrial Mile Rd, Columbus, OH 43228, USA e Institute for Superconducting and Electronic Materials, AIIM, University of Wollongong, North Wollongong, NSW 2519, Australia b
art ic l e i nf o
a b s t r a c t
Article history: Received 8 June 2015 Received in revised form 9 July 2015 Accepted 15 July 2015 Available online 17 July 2015
We present a new method for detecting damage to Nb barriers in MgB2 wires by using a four-contact probe. The transport measurements and scanning electron microscope images indicate that a newly identified jump in resistance means that there is damage to the Nb barrier. Damage detection is important for application because it allows us to avoid reactions between the filament and the sheath material, and to develop implementation methods for MgB2 with high critical current density. Our methods for damage detection proposed in this paper are simple, fast, and easy to use. & 2015 Published by Elsevier B.V.
Keywords: Magnesium diboride Damage detection Critical current
1. Introduction The superconductivity at high critical temperature (39 K) of cheap MgB2 material was discovered in 2001 by Akimitsu's group [1,2]. Various studies have shown that doping with SiC, C, and multi-walled carbon nanotubes promotes an increased irreversibility field (Birr) and increased critical current density (Jc) in high magnetic fields [3–7]. Furthermore, the high critical temperature (Tc) of MgB2 allows us to cool MgB2 wires by cryocooler, with no need to use expensive liquid helium. Pure Mg is a highly reactive material [8]. Its application in MgB2 wires requires barrier materials, which eliminate the reaction of Mg with the wire sheath [9– 11]. Although Nb is a widely used barrier material in MgB2 wires, breakage of the Nb during the wire drawing is a problem [12–14]. This damage causes the Mg to react with the wire shielding and reduces the amount of superconducting material in the filament. It also reduces the current carrying capability in MgB2 wires. In this article, we present a new method for detecting damage in Nb n
Corresponding authors. E-mail addresses: [email protected] (D. Gajda), [email protected] (M.S. Hossain). http://dx.doi.org/10.1016/j.matlet.2015.07.076 0167-577X/& 2015 Published by Elsevier B.V.
barriers. There is currently no information on any method that can detect such damage in the barriers of MgB2 wires. The lack of such a method significantly impedes research that is aimed at improving the superconducting and electrical properties in MgB2 wires. Two MgB2 wires with Nb barriers were made by Hyper Tech Research, Inc., using the powder-in-tube (PIT) method. The methods for producing wires and components of MgB2 materials are described in previous articles [14–16]. The samples were annealed at 700 °C in argon gas under isostatic pressure for 15 min at the Institute of High Pressure Physics laboratory (Table 1) [17]. Transport (15 Hz and AC current, IAC ¼260 mA) and magnetic (50 mT) measurements were performed using a physical properties measurement system (PPMS Model 7100, Quantum Design,) in the International Laboratory of High Magnetic Fields and Low Temperature [18]. The samples for transport measurements had a length of 12 mm. X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images were collected at the Institute of Low Temperature and Structure Research, Polish Academy of Sciences (PAS). The powder XRD pattern and elemental maps of undamaged MgB2 samples (insets) are shown in Fig. 1(a), demonstrating the lack of any detectable impurity phases in the MgB2 samples, apart
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D. Gajda et al. / Materials Letters 160 (2015) 81–84
Table 1 Technical parameters of MgB2 wires. Sample
Barrier
Mg:B
Sheath
Number of filaments/ fill factor
Diameter (mm)
A1 (damaged) A2 B1 (damaged) B2
Nb Nb Nb Nb
1.1: 1.1: 1.1: 1.1:
Monel Monel Copper Copper
18/15% 18/15% 6/19.4% 6/19.4%
0.83 0.83 0.83 0.83
2 2 2 2
Fig. 1. (a) XRD pattern of MgB2 powder extracted from wire and cross-sectional SEM images of samples (b) A1 and (c) B1. The insets of (a) are cross-sectional elemental mappings of the undamaged samples A2 (left) and B2 (right). The yellow circles in (b) and (c) indicate damage to the Nb barrier. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
from minor traces of MgO. Our SEM studies indicate that the problem of breakage in the Nb barriers in in-situ MgB2 wires. Samples A1 and B1 were cut to include the points in the wires where jump resistance at low temperature was observed, while Samples A2 and B2 were cut from sections of the same respective wires where jump resistance could not be observed. Cross-sectional SEM images of the MgB2 samples featuring the jump resistance show cracks in the Nb barrier (Fig. 1(b and c)). These
images demonstrate that the damage in the Nb barrier creates intermetallic phases outside the superconducting filaments (yellow circles in Fig. 1(b and c)). These phases contain Cu and Mg [19], because the matrix of the wires is made of copper and may create higher non-superconducting borides inside the filament to block the current [20]. Figs. 2(a) and 3(a) show the jumps in the resistance of the samples for which the SEM images reveal damage to the Nb bar-
D. Gajda et al. / Materials Letters 160 (2015) 81–84
83
Fig. 2. Transport R T (IAC ¼ 260 mA) curves for Samples A1 and A2 with Nb barriers: (a) in self-field and low magnetic fields, (b) in high magnetic fields, (c) at temperatures from 45 to 300 K (normal state). (d) Transport B T curves for samples A1 and A2, comparing the critical parameters of the corresponding samples with a damaged and a good Nb barrier.
rier of a filament (Fig. 1). The resistance jumps can be seen within the temperature range from 7.5 K to 10 K. These temperatures are similar to the critical temperature of Nb [21]. Such jumps were not reported in earlier articles. Moreover, in magnetic fields above 1 T, we do not see such jumps. This factor indicates that the jumps are associated with the Nb barrier, because the upper critical field (Bc2) of Nb is about 1 T [21]. In samples with good Nb barriers, we do not see any resistance jumps (Fig. 2(a–b) and Fig. 3(a–b)), and the transition from the superconducting state to the normal state is narrow. The measurements in Fig. 2(c) and Fig. 3(c) indicate that at temperatures from 45 K to 300 K, there is no obvious difference between the samples with good Nb barriers and the ones cut from the same wires with damaged Nb barriers. The value of the critical temperature is determined on the basis of the 50% criterion [22]. The results in Fig. 2(a–b) and Fig. 3(a–b) show that the values of Tc in samples with good barriers and samples with damaged Nb barriers are similar. The values of Birr and Bc2 have been determined with the criterion of 5% and 90%, respectively [22]. The Bc2 in samples with good barriers and samples with damaged barriers is similar, although a significant decrease in Birr can be seen in Sample A1 with a damaged barrier in comparison to Sample A2 with a good barrier. In a 3 T magnetic field, Sample A2 with a good barrier has a Birr that is higher by about 20% than that of the corresponding Sample A1 with a damaged barrier, and it is higher by 40% at 5 T and 60% at 7 T. In the undamaged sample B2, the Birr is higher than Birr in the corresponding damaged sample B1, e.g. at 3 T by about 15%, at 5 T by about 20%, and at 7 T by about 30–40%. In addition, we measured the critical current for samples
with good and damaged barriers and calculated the magnetic critical current density (Jcm) from the Bean model [23]. These results indicate that damage to the Nb barrier reduced Jcm by 5–15%. The transport critical current (Itc) was determined on the basis of the 1 μV/cm criterion [24]. The samples with good barriers have higher Itc than the samples with damaged barriers. Sample A2 (good barrier) has higher Itc by about 15–20% than Sample A1 (damaged barrier), while Sample B2 (good) has higher Itc by about 50% in comparison to Sample B1 (damaged). Our research has demonstrated that the sweep temperature method can detect damage to the Nb barrier. Based on these results, a damaged Nb barrier does not decrease Tc or Bc2, but does decrease Birr and Itc. We suppose that the jump resistance at low temperature (B ¼0 T) can reflect a number of factors, including vortex motion in the barrier, as well as the penetration of the current into the superconducting material through the wire shield and the damaged area. Damage to the barrier causes a significant reduction in the transport parameters, and this may be solved by increasing the thickness of the barriers. These results can be helpful not only for MgB2 wires, but also for detecting damage in any other low- or high-temperature superconductor. Moreover, these results may be the basis for developing an industrial method for detecting damage in MgB2 wires, which would make it possible to reliably obtain MgB2 wires with high Itc.
84
D. Gajda et al. / Materials Letters 160 (2015) 81–84
Fig. 3. Transport R T (IAC ¼ 260 mA) curves at 0T for samples B1 and B2 with Nb barriers: (a) in self-field and low magnetic fields, (b) in high magnetic fields, (c) at temperatures from 45 to 300 K (normal state). (d) Transport B T curves for samples B1 and B2, comparing the critical parameters of the corresponding samples with a damaged and good Nb barrier.
Acknowledgments This work was supported by the Institute of High Pressure Physics, PAS and the International Laboratory of High Magnetic Fields and Low Temperatures. It was also partially supported by the Australian Research Council (Grant no. DE130101247), and University of Wollongong and Australian Institute for Innovative Materials (AIIM) internal grants. The authors would like to thank Dr. Tania Silver for critical reading of this manuscript.
References [1] J. Nagamatsu, N. Nakagawa, T. Muranaka, Y. Zenitani, J. Akimitsu, Nature 410 (2001) 63–64. [2] Y. Takano, H. Takeya, H. Furii, H. Kumakura, T. Hatano, K. Toganok, H. Kito, H. Ihara, Appl. Phys. Lett. 78 (2001) 2914. [3] W. Haßler, M. Herrmann, C. Rodig, M. Schubert, K. Nenkov, B. Holzapfel, Supercond. Sci. Technol. 21 (2008) 062001. [4] W.X. Li, R. Zeng, J.L. Wang, Y. Li, S.X. Dou, J. Appl. Phys. 111 (2012) 07E135. [5] D. Patel, M. Maeda, S. Choi, S.J. Kim, M. Shahabuddin, J.M. Parakandy, M.S. A. Hossain, J.H. Kim, Scr. Mater. 88 (2014) 13–16. [6] Z. Ma, Y. Liu, W. Hu, Z. Gao, L. Yu, Z. Dong, Scr. Mater. 61 (2009) 836–839. [7] S. Barua, M.S.A. Hossain, Z. Ma, D. Patel, M. Mustapic, M. Somer, S. Acar, I. Kokal, A. Morawski, T. Cetner, D. Gajda, S.X. Dou, Scr. Mater. 104 (2015) 37–40. [8] J.L. Pelissier, Phys. Scr. 34 (1986) 838. [9] M.A. Susner, T.W. Daniels, M.D. Sumption, M.A. Rindfleisch, C.J. Thong, E. W. Collins, Supercond. Sci. Technol. 25 (2012) 065002. [10] K. Togano, J.M. Hur, A. Matsumoto, H. Kumakura, Supercond. Sci. Technol. 22
(2009) 015003. [11] A. Kario, A. Morawski, B.A. Glowacki, T. Lada, M. Smaga, R. Diduszko, D. Kolesnikov, A.J. Zaleski, A. Kondrat, D. Gajda, Acta Phys. Pol. A 111 (2007) 693. [12] T. Cetner, A. Morawski A, K. Adamczyk, M. Rindfleisch, M. Tomsic, A. Zaleski, D. Gajda, A. Presz, High Press. Res. 32 (2012) 419. [13] G. Aldica, I. Tiseanu, P. Badica, T. Craciunescu, M.A. Rindfleisch, in: A.M. Luiz (Ed.), Chapter 11 in Superconductor, Sciyo, Rijeka, 2010. 14 M. Tomsic, M. Rindfleisch, J. Yue, K. McFadden, J. Phillips, M.D. Sumption, M. Bhatia, S. Bohnenstiehl, E.W. Collings, Int. J. Appl. Ceram. Technol. 4 (2007) 250. [15] M.A. Susner, Y. Yang, M.D. Sumption, E.W. Collings, M.A. Rindfleisch, M. J. Tomsic, J.M. Marzik, Supercond. Sci. Technol. 24 (2011) 012001. [16] M.S.A. Hossain, C. Senatore, M.A. Rindfleisch, R. Flukiger, Supercond. Sci. Technol. 24 (2011) 075013. [17] A. Morawski, T. Łada, K. Przybylski, Physica C 387 (2003) 143. [18] D. Gajda, A. Morawski, A.J. Zaleski, W. Haßler, K. Nenkov, M.A. Rindfleisch, E. Zuchowska, G. Gajda, T. Czujko, T. Cetner, M.S.A. Hossain, J. Appl. Phys. 117 (2015) 173908. [19] M. Woźniak, K.L. Juda, S.C. Hopkins, D. Gajda, B.A. Glowacki, Supercond. Sci. Technol. 26 (2013) 105008. [20] T. Prikhna, M. Eisterer, W. Gawalek, A. Kozyrev, H.W. Weber, V. Sokolovsky, X. Chaud, J. Noudem, T. Habisreuther, V. Moshchil, M. Karpets, T. Basyuk, V. Kovylaev, J. Dellith, V. Sverdun, R. Kuznietsov, C. Shmidt, T. Vitovetskaya, L. Polikarpova, J. Supercond. Novel Magn. 26 (2013) 1569. [21] J.D. McCambridge, The Superconducting Properties of Niobium–Titanium Alloy Multilayers, Yale University thesis (Doctor of Philosophy), 1995. [22] G.Z. Li, Y. Yang, M.A. Susner, M.D. Sumption, E.W. Collings, Supercond. Sci. Technol. 25 (2012) 025001. [23] J. Horvat, W.K. Yeoh, J.H. Kim, S.X. Dou, Supercond. Sci. Technol. 21 (2008) 065003. [24] J.W. Ekin, Experimental Techniques for Low-Temperature Measurements, Oxford University Press, Oxford, 2006.