Penetration depth studies of organic and heavy fermion superconductors in the Pauli paramagnetic limit

被引:7
作者
Agosta, CC
Martin, C
Radovan, HA
Paim, EC
Murphy, TP
Tozer, SW
Cooley, JC
Schlueter, JA
Petrovic, C
机构
[1] Clark Univ, Dept Phys, Worcester, MA 01610 USA
[2] Natl High Magnet Field Lab, Tallahassee, FL 32310 USA
[3] Los Alamos Natl Lab, Los Alamos, NM 87545 USA
[4] Argonne Natl Lab, Argonne, IL 60439 USA
[5] Brookhaven Natl Lab, Dept Phys, Upton, NY 11973 USA
关键词
D O I
10.1016/j.jpcs.2005.10.156
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
We report penetration depth and resistivity measurements on a number of organic and heavy fermion superconductors in the Pauli paramagnetic limit using a self resonant tank circuit based on a tunnel diode oscillator (TDO). We call a superconductor Pauli limited when the interaction of the applied magnetic field with the electron spin limits the superconducting state, in contrast to orbital limiting, the traditional effect where vortices eventually destroy the superconducting state. In the Pauli limit, H-c2 can change from a second order to a first order phase transition at low temperatures, or in a very clean sample a new superconducting state with a spatially varying order parameter has been predicted, which we refer to as the FFLO state. We have done extensive experiments that show a range of Pauli limited behavior in anisotropic superconductors. Our results for alpha-(ET)(2)NH4Hg(SCN)(4), K-(ET)(2)Cu(NCS)(2), and CeCoIn5 show that the nature of the Pauli limiting state is sensitive to the mean freepath in the sample. In CeCoIn5 we have observed clear evidence of the FFLO state using our TDO method, and our data agrees with specific heat and magnetization measurements. We also show that the application of pressure will suppress the Pauli limiting in K-(ET)(2)CU(NCS)(2). (c) 2006 Elsevier Ltd. All rights reserved.
引用
收藏
页码:586 / 589
页数:4
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