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LaMnO3 bilayer
Materials Letters 236 (2019) 152–154
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Structure and magnetic properties of epitaxial Pt/LaMnO3 bilayer Haiou Wang ⇑, Chen Yang, Kunpeng Su, Shuai Huang, Dexuan Huo ⇑ Institute of Material Physics, Hangzhou Dianzi University, Hangzhou 310018, China
a r t i c l e
i n f o
Article history: Received 8 September 2018 Accepted 15 October 2018 Available online 15 October 2018 Keywords: Multilayer structure Epitaxial growth Ferromagnetism Exchange bias Transition-metal oxides
a b s t r a c t The structure and magnetic properties of Pt/LaMnO3 bilayer film grown on (0 0 1) MgO substrate have been studied. Structural investigations demonstrate that the bilayer film is well epitaxial and possesses high-quality growth. Magnetic measurements suggest that besides anti-ferromagnetic (AFM) state, unexpected ferromagnetic (FM) behavior is also observed clearly in the Pt/LaMnO3 bilayer structure. Moreover, exchange bias (EB) can also be found in the bilayer due to the formation of FM phase and the magnetic coupling between FM and AFM states. These interesting results provide a hopeful guidance for tuning the structure and magnetic properties of the strong-correlated materials. Ó 2018 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental details
Transition-metal oxides have received a lot of attention due to their fascinating physical properties, such as ferromagnetic (FM) transition and colossal magnetoresistance (CMR) in manganites, high temperature superconductivity (HTS) in cuprates and magnetic semiconductor in doped zinc oxides [1–3]. These attractive properties are associated with the complex interactions among the lattice, charge, spin and orbital degrees of freedom. The perovskite LaMnO3 is A-type anti-ferromagnetic (AFM) insulator [4,5]. It undergoes an AFM transition at Néel temperature TN about 140 K. As a transition-metal oxide, LaMnO3 has attracted renewed research interest for being an important component in a series of heterostructures that show unexpected physical properties, such as exchange bias (EB) effect and superconductivity in LaMnO3/LaNiO3 multilayers [6–9], interface magnetic coupling in LaMnO3/SrTiO3 multilayers [10], strong interfacial coupling in LaCoO3/LaMnO3 bilayers [11], FM state and metallic-like behavior at the interface of LaMnO3/SrMnO3 [12]. LaMnO3-based heterostructures have exhibited rich and interesting physical phenomena. However, most of them are limited to all-oxide mutilayer structures. In this work, we report the growth of Pt/LaMnO3 bilayer and investigate the structure and magnetic properties of the bilayer structure.
A bilayer structure of Pt (3 nm)/LaMnO3(100 nm) was grown on single crystal MgO (0 0 1) substrate by pulsed laser deposition, using a KrF excimer laser (k = 248 nm) with growth control by in-situ reflection high-energy electron diffraction (RHEED). The LaMnO3 layer was deposited at temperatures of 720 °C and oxygen pressures of 50 Pa and Pt layer was grown at temperatures of 300 °C and argon pressures of 1 Pa. The sublayer thickness was controlled by the number of applied laser pulses. Surface morphology was measured by atomic force microscopy and the crystalline structure was characterized using the high resolution X-ray diffraction (XRD). This experiment was performed at Beijing Synchrotron Radiation Facility (BSRF) with X-ray wavelength of 0.15405 nm. Magnetism measurements were performed in a Physical Property Measurement System with a vibrating sample magnetometer (VSM) option.
⇑ Corresponding authors. E-mail addresses: [email protected] (H. Wang), [email protected] (D. Huo). https://doi.org/10.1016/j.matlet.2018.10.092 0167-577X/Ó 2018 Elsevier B.V. All rights reserved.
3. Results and discussion Fig. 1 shows the high resolution XRD pattern in h 2h mode around (0 0 2) peak of MgO substrate. Inset of Fig. 1 exhibits an enlarged fragment of low angle reflection. One can find the (0 0 2) peaks of LaMnO3 layer and Pt ultrathin layer. Only (0 0 l) reflections indicate the high epitaxial quality of Pt/LaMnO3 bilayer. In previous reports on ultrathin Pt-based mutilayers [13], the diffraction peak of Pt layer is hard to be observed. In order to observe the reflection peak of ultrathin Pt layer, the bilayer structure is studied by synchrotron radiation XRD with high resolution. The out-of-plane lattice parameters of two component layers
H. Wang et al. / Materials Letters 236 (2019) 152–154
Fig. 1. High resolution X-ray diffraction patterns of Pt/LaMnO3 bilayer deposited on MgO (0 0 1) substrate. Inset shows an enlarged fragment of low angle diffraction.
(Pt and LaMnO3 layers) and the related lattice strain can be obtained from the XRD h 2h scan in Fig. 1. The out-of-plane strain e\ can be calculated using the formula e\ = (c cbulk)/cbulk, where c is out-of-plane lattice parameter and cbulk is the bulk unstressed lattice parameter. Perovskite LaMnO3 has an orthorhombic structure (space group Pnma) with a pseudocubic lattice parameter of
153
cbulk-LaMnO3 = 0.3942 nm [14]. For LaMnO3 layer, the out-of-plane lattice parameter (cLaMnO3 = 0.3862 nm) was smaller than cbulk-LaMnO3 (0.3942 nm), suggesting an out-of-plane compression of LaMnO3 lattice. The corresponding strain (e\ 2.03%) show that LaMnO3 layer has slight tensile strain. For Pt layer, the (0 0 2) peak of Pt layer shift towards lower angle, suggesting an out-of-plane stretching of Pt lattice, the out-of-plane lattice parameter (cPt = 0.4196 nm) was larger than cbulk-Pt (0.3923 nm). The corresponding strain values (e\ 6.96%) suggest that Pt layer is under compressive strain. To characterize the surface morphology and roughness, we perform atomic force microscopy measurement on Pt/LaMnO3 bilayer. Fig. 2 shows the atomic force microscopy topographic image of the bilayer on (0 0 1) MgO. The scan was obtained using an area of 2 2 mm2. The bilayer exhibits very smooth surface with rootmean-square (rms) surface roughness of 0.329 nm. In a few words, structural characterizations (see Figs. 1 and 2) demonstrate the homogeneous growth and high epitaxial quality of the bilayer. Fig. 3(a) shows the magnetization versus temperature (M-T) curves after zero field-cooling (ZFC) and field-cooling (FC) in 0.1 KOe field process for the Pt/LaMnO3 bilayer, with the measuring fields of 0.1 KOe. The sharp rise in magnetization corresponds to the paramagnetic (PM) to FM transition at Curie temperature TC 160 K. It also exhibits a sharp drop in magnetization in ZFC M-T curve, which corresponds to a FM to AFM transition at Néel temperature TN 40 K. The TC and TN can be obtained in the plot of dM/dT versus temperature, as shown in the inset of Fig. 3(a). Moreover, The bifurcation of FC and ZFC M-T curves at the freezing
Fig. 2. Atomic force microscopy image plotted for an area of 2 mm 2 mm of Pt/LaMnO3 bilayer on MgO (0 0 1) substrate.
Fig. 3. (a) Magnetization versus temperature curves of Pt/LaMnO3 bilayer after ZFC and FC in 0.1 KOe field process. Inset of (a): the temperature dependence of the temperature derivative of magnetization, dM/dT. (b) Magnetization versus field loop at 5 K for Pt/LaMnO3 bilayer. Inset of (b): the enlarged fragment of low field magnetization. All magnetic measurements are performed by applying the field parallel to the sample plane.
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H. Wang et al. / Materials Letters 236 (2019) 152–154
and the appearance of EB in Pt/LaMnO3 bilayer is closely related to strain-controlled orbital ordering. 4. Conclusion High-quality Pt/LaMnO3 bilayer has been synthesized. The bilayer exhibits unexpected FM properties and EB effect. These interesting results can be explained by strain-controlled orbital state. Our research findings are beneficial for understanding of the origin of FM properties and open a promising route for manipulating the magnetic properties of LaMnO3-based strong correlated systems. Acknowledgement
Fig. 4. Magnetization versus magnetic field loops of Pt/LaMnO3 bilayer at 5 K after ZFC and FC in 0.1 KOe field process from room temperature. Inset displays the enlarged fragment of low field magnetization.
temperature Tf, as indicated by a arrow, represents the emergence of spin/cluster glass state[15,16]. Interestingly, unexpected FM properties has been observed in the bilayer (Remarkably, the LaMnO3 is AFM insulator, while Pt is PM metal). In Fig. 3(b), a typical FM nature is observed in the Pt/LaMnO3 bilayer at temperature of 5 K. The coercive fields HC at 5 K is 160 Oe. The magnetic hysteresis curve at 5 K (see Fig. 3(b)) exhibits relative square loop with clear hysteresis centered at zero field. An enlarged fragment of low field magnetization is shown in the inset of Fig. 3(b). Fig. 4 shows the magnetization versus field (M-H) loops after zero field-cooling (ZFC) and field-cooling (FC) in 0.1 KOe field process at temperature of 5 K for the Pt/LaMnO3 bilayer. In Fig. 4, a very small shift of the center of hysteresis loop along the magnetic field axis is observed after FC process from room temperature under 0.1 KOe field. While for the ZFC process, the hysteresis loop is normal. This phenomenon represents the typical signature of EB. At 5 K, HEB of 15 Oe is obtained under 0.1 KOe cooling field. The origin of FM behavior in LaMnO3-based mutilayer structures has been proved by various experimental results [6,7,12,17,18] and theoretical calculations [19,20], which derives from the orbital ordering controlled by strain state. According to the structural characterization mentioned above, the LaMnO3 layer is under tensile strain, which is the same with previous related report [19]. The EB effect in the bilayer is induced by the coupling between FM and AFM states. Therefore, the formation of FM state
This work was supported by the National Natural Science Foundation of China (Grant Nos. 11604067, 11574066, 51601049, 11704091). We thank colleagues from Shanghai Synchrotron Radiation Facility and Beijing Synchrotron Radiation Facility for their help in XRD experiments. References [1] M. Imada, A. Fujimori, Y. Tokura, Rev. Mod. Phys. 70 (1998) 1039. [2] J. Mannhart, D.G. Schlom, Science 327 (2010) 1607. [3] S.A. Wolf, D.D. Awschalom, R.A. Buhrman, J.M. Daughton, S. von Molnar, M.L. Roukes, A.Y. Chtchelkanova, D.M. Treger, Science 294 (2001) 1488. [4] E.O. Wollan, W.C. Koehler, Phys. Rev. 100 (1955) 545. [5] C. Ritter, M.R. Ibarra, J.M. De Teresa, P.A. Algarabel, C. Marquina, J. Blasco, J. García, S. Oseroff, S.-W. Cheong, Phys. Rev. B 56 (1997) 8902. [6] M. Gibert, P. Zubko, R. Scherwitzl, J. Iniguez, J.M. Triscone, Nat. Mater. 11 (2012) 1958. [7] J. Zang, G. Zhou, Y. Bai, Z. Quan, X. Xu, Sci. Rep. 7 (2017) 10557. [8] J. Chaloupka, G. Khaliullin, Phys. Rev. Lett. 100 (2008) 016404. [9] Haoming Wei, Jose luis barzola-quiquia, chang yang, christian patzig, thomas h€oche, pablo esquinazi, marius grundmann, and michael lorenz, Appl. Phys. Lett. 110 (2017) 102403. [10] F. Cossu, J. Jilili, U. Schwingenschlögl, Adv. Mater. Interfaces 1 (2014) 1400057. [11] José Manuel Vila-Fungueiriño, Beatriz Rivas-Murias, Francisco Rivadulla, Thin Solid Films 553 (2014) 81. [12] S. Smadici, P. Abbamonte, A. Bhattacharya, X. Zhai, B. Jiang, A. Rusydi, J.N. Eckstein, S.D. Bader, J.M. Zuo, Phys. Rev. Lett. 99 (2007) 196404. [13] Dazhi Hou, Zhiyong Qiu, Joseph Barker, Koji Sato, Kei Yamamoto, Saül Vélez, Juan M. Gomez-Perez, Luis E. Hueso, Fèlix Casanova, Eiji Saitoh, Phys. Rev. Lett. 118 (2017) 147202. [14] V. Skumryev, F. Ott, J.M.D. Coey, A. Anane, J.-P. Renard, L. Pinsard-Gaudart, A. Revcolevschi, Eur. Phys. J. B 11 (1999) 401. [15] S. Liang, J.R. Sun, J. Wang, B.G. Shen, Appl. Phys. Lett. 95 (2009) 182509. [16] H. Wang, W. Yang, K. Su, D. Huo, W. Tan, J. Alloy. Compd. 648 (2015) 966. [17] X.R. Wang, C.J. Li, W.M. Lü, Science 349 (2015) 716. [18] A.M. Zhang, S.L. Cheng, J.G. Lin, X.S. Wu, J. Appl. Phys. 117 (2015) 17B325. [19] E. Pavarini, E. Koch, Phys. Rev. Lett. 104 (2010) 086402. [20] B.R.K. Nanda, S. Satpathy, Phys. Rev. B 81 (2010) 174423.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Structure and magnetic properties of epitaxial Pt/LaMnO3 bilayer Haiou Wang ⇑, Chen Yang, Kunpeng Su, Shuai Huang, Dexuan Huo ⇑ Institute of Material Physics, Hangzhou Dianzi University, Hangzhou 310018, China
a r t i c l e
i n f o
Article history: Received 8 September 2018 Accepted 15 October 2018 Available online 15 October 2018 Keywords: Multilayer structure Epitaxial growth Ferromagnetism Exchange bias Transition-metal oxides
a b s t r a c t The structure and magnetic properties of Pt/LaMnO3 bilayer film grown on (0 0 1) MgO substrate have been studied. Structural investigations demonstrate that the bilayer film is well epitaxial and possesses high-quality growth. Magnetic measurements suggest that besides anti-ferromagnetic (AFM) state, unexpected ferromagnetic (FM) behavior is also observed clearly in the Pt/LaMnO3 bilayer structure. Moreover, exchange bias (EB) can also be found in the bilayer due to the formation of FM phase and the magnetic coupling between FM and AFM states. These interesting results provide a hopeful guidance for tuning the structure and magnetic properties of the strong-correlated materials. Ó 2018 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental details
Transition-metal oxides have received a lot of attention due to their fascinating physical properties, such as ferromagnetic (FM) transition and colossal magnetoresistance (CMR) in manganites, high temperature superconductivity (HTS) in cuprates and magnetic semiconductor in doped zinc oxides [1–3]. These attractive properties are associated with the complex interactions among the lattice, charge, spin and orbital degrees of freedom. The perovskite LaMnO3 is A-type anti-ferromagnetic (AFM) insulator [4,5]. It undergoes an AFM transition at Néel temperature TN about 140 K. As a transition-metal oxide, LaMnO3 has attracted renewed research interest for being an important component in a series of heterostructures that show unexpected physical properties, such as exchange bias (EB) effect and superconductivity in LaMnO3/LaNiO3 multilayers [6–9], interface magnetic coupling in LaMnO3/SrTiO3 multilayers [10], strong interfacial coupling in LaCoO3/LaMnO3 bilayers [11], FM state and metallic-like behavior at the interface of LaMnO3/SrMnO3 [12]. LaMnO3-based heterostructures have exhibited rich and interesting physical phenomena. However, most of them are limited to all-oxide mutilayer structures. In this work, we report the growth of Pt/LaMnO3 bilayer and investigate the structure and magnetic properties of the bilayer structure.
A bilayer structure of Pt (3 nm)/LaMnO3(100 nm) was grown on single crystal MgO (0 0 1) substrate by pulsed laser deposition, using a KrF excimer laser (k = 248 nm) with growth control by in-situ reflection high-energy electron diffraction (RHEED). The LaMnO3 layer was deposited at temperatures of 720 °C and oxygen pressures of 50 Pa and Pt layer was grown at temperatures of 300 °C and argon pressures of 1 Pa. The sublayer thickness was controlled by the number of applied laser pulses. Surface morphology was measured by atomic force microscopy and the crystalline structure was characterized using the high resolution X-ray diffraction (XRD). This experiment was performed at Beijing Synchrotron Radiation Facility (BSRF) with X-ray wavelength of 0.15405 nm. Magnetism measurements were performed in a Physical Property Measurement System with a vibrating sample magnetometer (VSM) option.
⇑ Corresponding authors. E-mail addresses: [email protected] (H. Wang), [email protected] (D. Huo). https://doi.org/10.1016/j.matlet.2018.10.092 0167-577X/Ó 2018 Elsevier B.V. All rights reserved.
3. Results and discussion Fig. 1 shows the high resolution XRD pattern in h 2h mode around (0 0 2) peak of MgO substrate. Inset of Fig. 1 exhibits an enlarged fragment of low angle reflection. One can find the (0 0 2) peaks of LaMnO3 layer and Pt ultrathin layer. Only (0 0 l) reflections indicate the high epitaxial quality of Pt/LaMnO3 bilayer. In previous reports on ultrathin Pt-based mutilayers [13], the diffraction peak of Pt layer is hard to be observed. In order to observe the reflection peak of ultrathin Pt layer, the bilayer structure is studied by synchrotron radiation XRD with high resolution. The out-of-plane lattice parameters of two component layers
H. Wang et al. / Materials Letters 236 (2019) 152–154
Fig. 1. High resolution X-ray diffraction patterns of Pt/LaMnO3 bilayer deposited on MgO (0 0 1) substrate. Inset shows an enlarged fragment of low angle diffraction.
(Pt and LaMnO3 layers) and the related lattice strain can be obtained from the XRD h 2h scan in Fig. 1. The out-of-plane strain e\ can be calculated using the formula e\ = (c cbulk)/cbulk, where c is out-of-plane lattice parameter and cbulk is the bulk unstressed lattice parameter. Perovskite LaMnO3 has an orthorhombic structure (space group Pnma) with a pseudocubic lattice parameter of
153
cbulk-LaMnO3 = 0.3942 nm [14]. For LaMnO3 layer, the out-of-plane lattice parameter (cLaMnO3 = 0.3862 nm) was smaller than cbulk-LaMnO3 (0.3942 nm), suggesting an out-of-plane compression of LaMnO3 lattice. The corresponding strain (e\ 2.03%) show that LaMnO3 layer has slight tensile strain. For Pt layer, the (0 0 2) peak of Pt layer shift towards lower angle, suggesting an out-of-plane stretching of Pt lattice, the out-of-plane lattice parameter (cPt = 0.4196 nm) was larger than cbulk-Pt (0.3923 nm). The corresponding strain values (e\ 6.96%) suggest that Pt layer is under compressive strain. To characterize the surface morphology and roughness, we perform atomic force microscopy measurement on Pt/LaMnO3 bilayer. Fig. 2 shows the atomic force microscopy topographic image of the bilayer on (0 0 1) MgO. The scan was obtained using an area of 2 2 mm2. The bilayer exhibits very smooth surface with rootmean-square (rms) surface roughness of 0.329 nm. In a few words, structural characterizations (see Figs. 1 and 2) demonstrate the homogeneous growth and high epitaxial quality of the bilayer. Fig. 3(a) shows the magnetization versus temperature (M-T) curves after zero field-cooling (ZFC) and field-cooling (FC) in 0.1 KOe field process for the Pt/LaMnO3 bilayer, with the measuring fields of 0.1 KOe. The sharp rise in magnetization corresponds to the paramagnetic (PM) to FM transition at Curie temperature TC 160 K. It also exhibits a sharp drop in magnetization in ZFC M-T curve, which corresponds to a FM to AFM transition at Néel temperature TN 40 K. The TC and TN can be obtained in the plot of dM/dT versus temperature, as shown in the inset of Fig. 3(a). Moreover, The bifurcation of FC and ZFC M-T curves at the freezing
Fig. 2. Atomic force microscopy image plotted for an area of 2 mm 2 mm of Pt/LaMnO3 bilayer on MgO (0 0 1) substrate.
Fig. 3. (a) Magnetization versus temperature curves of Pt/LaMnO3 bilayer after ZFC and FC in 0.1 KOe field process. Inset of (a): the temperature dependence of the temperature derivative of magnetization, dM/dT. (b) Magnetization versus field loop at 5 K for Pt/LaMnO3 bilayer. Inset of (b): the enlarged fragment of low field magnetization. All magnetic measurements are performed by applying the field parallel to the sample plane.
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H. Wang et al. / Materials Letters 236 (2019) 152–154
and the appearance of EB in Pt/LaMnO3 bilayer is closely related to strain-controlled orbital ordering. 4. Conclusion High-quality Pt/LaMnO3 bilayer has been synthesized. The bilayer exhibits unexpected FM properties and EB effect. These interesting results can be explained by strain-controlled orbital state. Our research findings are beneficial for understanding of the origin of FM properties and open a promising route for manipulating the magnetic properties of LaMnO3-based strong correlated systems. Acknowledgement
Fig. 4. Magnetization versus magnetic field loops of Pt/LaMnO3 bilayer at 5 K after ZFC and FC in 0.1 KOe field process from room temperature. Inset displays the enlarged fragment of low field magnetization.
temperature Tf, as indicated by a arrow, represents the emergence of spin/cluster glass state[15,16]. Interestingly, unexpected FM properties has been observed in the bilayer (Remarkably, the LaMnO3 is AFM insulator, while Pt is PM metal). In Fig. 3(b), a typical FM nature is observed in the Pt/LaMnO3 bilayer at temperature of 5 K. The coercive fields HC at 5 K is 160 Oe. The magnetic hysteresis curve at 5 K (see Fig. 3(b)) exhibits relative square loop with clear hysteresis centered at zero field. An enlarged fragment of low field magnetization is shown in the inset of Fig. 3(b). Fig. 4 shows the magnetization versus field (M-H) loops after zero field-cooling (ZFC) and field-cooling (FC) in 0.1 KOe field process at temperature of 5 K for the Pt/LaMnO3 bilayer. In Fig. 4, a very small shift of the center of hysteresis loop along the magnetic field axis is observed after FC process from room temperature under 0.1 KOe field. While for the ZFC process, the hysteresis loop is normal. This phenomenon represents the typical signature of EB. At 5 K, HEB of 15 Oe is obtained under 0.1 KOe cooling field. The origin of FM behavior in LaMnO3-based mutilayer structures has been proved by various experimental results [6,7,12,17,18] and theoretical calculations [19,20], which derives from the orbital ordering controlled by strain state. According to the structural characterization mentioned above, the LaMnO3 layer is under tensile strain, which is the same with previous related report [19]. The EB effect in the bilayer is induced by the coupling between FM and AFM states. Therefore, the formation of FM state
This work was supported by the National Natural Science Foundation of China (Grant Nos. 11604067, 11574066, 51601049, 11704091). We thank colleagues from Shanghai Synchrotron Radiation Facility and Beijing Synchrotron Radiation Facility for their help in XRD experiments. References [1] M. Imada, A. Fujimori, Y. Tokura, Rev. Mod. Phys. 70 (1998) 1039. [2] J. Mannhart, D.G. Schlom, Science 327 (2010) 1607. [3] S.A. Wolf, D.D. Awschalom, R.A. Buhrman, J.M. Daughton, S. von Molnar, M.L. Roukes, A.Y. Chtchelkanova, D.M. Treger, Science 294 (2001) 1488. [4] E.O. Wollan, W.C. Koehler, Phys. Rev. 100 (1955) 545. [5] C. Ritter, M.R. Ibarra, J.M. De Teresa, P.A. Algarabel, C. Marquina, J. Blasco, J. García, S. Oseroff, S.-W. Cheong, Phys. Rev. B 56 (1997) 8902. [6] M. Gibert, P. Zubko, R. Scherwitzl, J. Iniguez, J.M. Triscone, Nat. Mater. 11 (2012) 1958. [7] J. Zang, G. Zhou, Y. Bai, Z. Quan, X. Xu, Sci. Rep. 7 (2017) 10557. [8] J. Chaloupka, G. Khaliullin, Phys. Rev. Lett. 100 (2008) 016404. [9] Haoming Wei, Jose luis barzola-quiquia, chang yang, christian patzig, thomas h€oche, pablo esquinazi, marius grundmann, and michael lorenz, Appl. Phys. Lett. 110 (2017) 102403. [10] F. Cossu, J. Jilili, U. Schwingenschlögl, Adv. Mater. Interfaces 1 (2014) 1400057. [11] José Manuel Vila-Fungueiriño, Beatriz Rivas-Murias, Francisco Rivadulla, Thin Solid Films 553 (2014) 81. [12] S. Smadici, P. Abbamonte, A. Bhattacharya, X. Zhai, B. Jiang, A. Rusydi, J.N. Eckstein, S.D. Bader, J.M. Zuo, Phys. Rev. Lett. 99 (2007) 196404. [13] Dazhi Hou, Zhiyong Qiu, Joseph Barker, Koji Sato, Kei Yamamoto, Saül Vélez, Juan M. Gomez-Perez, Luis E. Hueso, Fèlix Casanova, Eiji Saitoh, Phys. Rev. Lett. 118 (2017) 147202. [14] V. Skumryev, F. Ott, J.M.D. Coey, A. Anane, J.-P. Renard, L. Pinsard-Gaudart, A. Revcolevschi, Eur. Phys. J. B 11 (1999) 401. [15] S. Liang, J.R. Sun, J. Wang, B.G. Shen, Appl. Phys. Lett. 95 (2009) 182509. [16] H. Wang, W. Yang, K. Su, D. Huo, W. Tan, J. Alloy. Compd. 648 (2015) 966. [17] X.R. Wang, C.J. Li, W.M. Lü, Science 349 (2015) 716. [18] A.M. Zhang, S.L. Cheng, J.G. Lin, X.S. Wu, J. Appl. Phys. 117 (2015) 17B325. [19] E. Pavarini, E. Koch, Phys. Rev. Lett. 104 (2010) 086402. [20] B.R.K. Nanda, S. Satpathy, Phys. Rev. B 81 (2010) 174423.