- Email: [email protected]
Thermal conductivity of RNi2B2C (R=Er, Tm, and Gd) systems
Physica
ELSEVIER
C 34 l-348
Thermal Conductivity of RNisB# Shixun Cao
l, Shuji Sakai
(2000)
75 I-752
(R=Er, Tm, and Gd) Systems
, Katsuhiko Nishimura and Katsunori Mori
Faculty of Engineering, Toyama University, 3190 Gofuku, Toyama 9398555, Japan The temperaturedependencesof thexmalconductivityhave been mezuuredfor B&B&I (B.=JSr,Tm, and Gd) systemsunder variousapplied magneticfields. The temperaturedependencesof thermalconductivityof RNi,B& (FkEr and Tm) showed a change in slope at !I’,. In zaro magneticseld, the thermal umductivityof EkNilB& and GdNilB& showed small peaks at TN, which disappeared under applied magnetic fields. At temperatures below Z’,, the value of thermal umductivity in an applied magnetic field was larger than that in zero field.
1. Introduction The recent discovery of quaternary nickel borecarbide compounds, R.NisB& (R=Y or rare earth), have attracted a great deal of attention because of the coexistence of superconducting and magnetic ground states[l,2]. Since thermal conductivity (T.C.) has nonzero value in both normal and superconducting states, investige tions on T.C. can provide various information on the interplay between electrons and phonons and scattering of the both by defects and impurities. Therefore, the heat transport property in quaternary nickel borocarbide superconductors is intimately related to the mechanism of superconductivity as well as those in conventional and high-T, superconductors. Nevertheless so&r, there seems to be only one published report[3] on T.C. study on nickel borocarbide superconductors. In this paper, we present the results of T.C.in RNirBrC (R=Er, Tm, and Gd) systems. 2. Experimental Samples of RNisBsC (R=Er, Tm, and Gd) were prepared by arc-melting method under argon atmosphere. The resulting ingots were then annealed for 72 hours at 1373 K. Powder Xray diffraction measurement con9rmed that the *Email: sxaoQeng.toyama-u.ac.jp.
This work hae been supported by the Grants-in-Aid for Scientific F&ear& from the Japan Society for the Promotion of Science (JSPS), under the JSPS Postdoctoral Fellowehip Program for Foreign Researehere. 0921-4534/00/$ PII SO92
- see front matter 0 2000
I -4534(00)00675-4
Elsevier
Science
B.V
samples were predominantly single phase. T.C. was measured by the usual steady-state heat flow method[4] in a twofold vacuum system. Temperature of the whole system was controlled using a Lake Shore Model 340 Temperature Controller with temperature stability better than f0.05K. The samples were in the form of a parallelepiped with dimensions 1.50x1.50x10.0mm9. Two Cernox thermometers were used to measure the temperature gradient of both ends of the samples. The sensitivity of T.C. measurement in the set up was about 0.5 mWcm-‘K-l. 3. Results
and Discussion
Fire 1 shows the temperature dependence of T.C. in RNisBsC (R,=Er, Tm, and Gd) systems. The value of T.C. with R=Tm was almost twice larger than those with R=Er and Gd. The T.C. of RI%&&! (R=Er and Tm) showed a change in slope at T, - 10.5K, and the T.C. of ErNirBsC and GdNi2BsC showed small peaks at TN - 5K and 19K, respectively, which is similar to the results of RN@& (R=Y and Ho) reported by Sera[3] et al. These characteristic temperatures, T, and TN, obtained from T.C. were consistent with those determined from other measurements[5]. The value of T.C. decreasing faster below Tc could be attributed to the decrease of contribution of electrons to T.C. because of the formation of Cooper pairs. Temperature dependence of T.C. of ErNirBrC under various magnetic fields are shown in Fig.
All rights reserved
S Cao et al./Ph,~srcu C M-343
152
80
.
,
.
,
.
,
.
(2000)751-752
25,
8 _w
1
RN&B&
ErNi2B2C
Tm l Er OGd
q
Oo I.
5‘.
0 H=30 kOe
_ A H=lOkOe A H= 5kOe .H= OkOe
10 1.
15 1
*
20 1.
25
Temperature(K)
Figure 1. Temperature dependence of T.C.in RNizB# (R=Er, Tm, and Gd) systems.
2. In zero magnetic field, the T.C.of ErNizB& showed a small peak at TN,whichdhppeared under applied magnetic fields. At temperatures below Tc,the values of T.C.inapplied magnetic fields were larger than that in zero field, which could be attributed to the increase of contribution of electrons to T.C.because of the pair breaking by magnetic field. REFERENCES 1. R. Nagarajan, C. Mazudar, Z. Hossain, SK. Dhar, K.V. Gopalakishnan, L.C. Gupta, C. Godart, B.D. Padalia, and R. Vijayarahavan, Phys. Rev. Lett. 72 (1994) 274.
OO3 Temperature(K)
Fiie 2. Temperature dependence of T.C.of ErNi&C under various magnetic fields.
R.J. Cava, H. ‘Ikkagi, B. Batlogg, H.W. Zandbergen, J.J. Krajewski, W.F. Peck, Jr., R.B. van Dover, R.J. Felder, T. Siegrlst, K. Mizuhashi, J.O. Lee, II. Eisaki, S.A. Carter, and S. Uchlda, Nature(London) 367 (1994) 146. M. Sera, S. Kobayashi, M. Hiroi, N. Kobayashi, H. Takeya, and K. Kadowakl, Phys. Rev. B 54 (1996) 3062. T. Mamiya, J. Phys. Sot. Jpn. 21(1966) 1032. J.W. Lynn, S. Skanthakumar, Q. Huang, S.K. Sii, Z. Hossain, L.C. Gupta, R. Nagarajan, and C. Godart, Phys. Rev. B 55 (1997) 6564.
ELSEVIER
C 34 l-348
Thermal Conductivity of RNisB# Shixun Cao
l, Shuji Sakai
(2000)
75 I-752
(R=Er, Tm, and Gd) Systems
, Katsuhiko Nishimura and Katsunori Mori
Faculty of Engineering, Toyama University, 3190 Gofuku, Toyama 9398555, Japan The temperaturedependencesof thexmalconductivityhave been mezuuredfor B&B&I (B.=JSr,Tm, and Gd) systemsunder variousapplied magneticfields. The temperaturedependencesof thermalconductivityof RNi,B& (FkEr and Tm) showed a change in slope at !I’,. In zaro magneticseld, the thermal umductivityof EkNilB& and GdNilB& showed small peaks at TN, which disappeared under applied magnetic fields. At temperatures below Z’,, the value of thermal umductivity in an applied magnetic field was larger than that in zero field.
1. Introduction The recent discovery of quaternary nickel borecarbide compounds, R.NisB& (R=Y or rare earth), have attracted a great deal of attention because of the coexistence of superconducting and magnetic ground states[l,2]. Since thermal conductivity (T.C.) has nonzero value in both normal and superconducting states, investige tions on T.C. can provide various information on the interplay between electrons and phonons and scattering of the both by defects and impurities. Therefore, the heat transport property in quaternary nickel borocarbide superconductors is intimately related to the mechanism of superconductivity as well as those in conventional and high-T, superconductors. Nevertheless so&r, there seems to be only one published report[3] on T.C. study on nickel borocarbide superconductors. In this paper, we present the results of T.C.in RNirBrC (R=Er, Tm, and Gd) systems. 2. Experimental Samples of RNisBsC (R=Er, Tm, and Gd) were prepared by arc-melting method under argon atmosphere. The resulting ingots were then annealed for 72 hours at 1373 K. Powder Xray diffraction measurement con9rmed that the *Email: sxaoQeng.toyama-u.ac.jp.
This work hae been supported by the Grants-in-Aid for Scientific F&ear& from the Japan Society for the Promotion of Science (JSPS), under the JSPS Postdoctoral Fellowehip Program for Foreign Researehere. 0921-4534/00/$ PII SO92
- see front matter 0 2000
I -4534(00)00675-4
Elsevier
Science
B.V
samples were predominantly single phase. T.C. was measured by the usual steady-state heat flow method[4] in a twofold vacuum system. Temperature of the whole system was controlled using a Lake Shore Model 340 Temperature Controller with temperature stability better than f0.05K. The samples were in the form of a parallelepiped with dimensions 1.50x1.50x10.0mm9. Two Cernox thermometers were used to measure the temperature gradient of both ends of the samples. The sensitivity of T.C. measurement in the set up was about 0.5 mWcm-‘K-l. 3. Results
and Discussion
Fire 1 shows the temperature dependence of T.C. in RNisBsC (R,=Er, Tm, and Gd) systems. The value of T.C. with R=Tm was almost twice larger than those with R=Er and Gd. The T.C. of RI%&&! (R=Er and Tm) showed a change in slope at T, - 10.5K, and the T.C. of ErNirBsC and GdNi2BsC showed small peaks at TN - 5K and 19K, respectively, which is similar to the results of RN@& (R=Y and Ho) reported by Sera[3] et al. These characteristic temperatures, T, and TN, obtained from T.C. were consistent with those determined from other measurements[5]. The value of T.C. decreasing faster below Tc could be attributed to the decrease of contribution of electrons to T.C. because of the formation of Cooper pairs. Temperature dependence of T.C. of ErNirBrC under various magnetic fields are shown in Fig.
All rights reserved
S Cao et al./Ph,~srcu C M-343
152
80
.
,
.
,
.
,
.
(2000)751-752
25,
8 _w
1
RN&B&
ErNi2B2C
Tm l Er OGd
q
Oo I.
5‘.
0 H=30 kOe
_ A H=lOkOe A H= 5kOe .H= OkOe
10 1.
15 1
*
20 1.
25
Temperature(K)
Figure 1. Temperature dependence of T.C.in RNizB# (R=Er, Tm, and Gd) systems.
2. In zero magnetic field, the T.C.of ErNizB& showed a small peak at TN,whichdhppeared under applied magnetic fields. At temperatures below Tc,the values of T.C.inapplied magnetic fields were larger than that in zero field, which could be attributed to the increase of contribution of electrons to T.C.because of the pair breaking by magnetic field. REFERENCES 1. R. Nagarajan, C. Mazudar, Z. Hossain, SK. Dhar, K.V. Gopalakishnan, L.C. Gupta, C. Godart, B.D. Padalia, and R. Vijayarahavan, Phys. Rev. Lett. 72 (1994) 274.
OO3 Temperature(K)
Fiie 2. Temperature dependence of T.C.of ErNi&C under various magnetic fields.
R.J. Cava, H. ‘Ikkagi, B. Batlogg, H.W. Zandbergen, J.J. Krajewski, W.F. Peck, Jr., R.B. van Dover, R.J. Felder, T. Siegrlst, K. Mizuhashi, J.O. Lee, II. Eisaki, S.A. Carter, and S. Uchlda, Nature(London) 367 (1994) 146. M. Sera, S. Kobayashi, M. Hiroi, N. Kobayashi, H. Takeya, and K. Kadowakl, Phys. Rev. B 54 (1996) 3062. T. Mamiya, J. Phys. Sot. Jpn. 21(1966) 1032. J.W. Lynn, S. Skanthakumar, Q. Huang, S.K. Sii, Z. Hossain, L.C. Gupta, R. Nagarajan, and C. Godart, Phys. Rev. B 55 (1997) 6564.