Magnetic properties of λ- BETS 2 ( F e x Ga 1 − x ) Cl 4 exhibiting a superconductor-to-insulator transition ( 0.35 x 0.5 )
Magnetic properties of λ- BETS 2 ( F e x Ga 1 − x ) Cl 4 exhibiting a superconductor-to-insulator transition ( 0.35 x 0.5 )
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表现出超导体到绝缘体转变的 λ-BETS 2 (F ex Ga 1 − x ) Cl 4 的磁性 (0.35 x 0.5)
DOI：
10.1103/physrevb.61.111
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发表时间：
2000
影响因子：
3.7
通讯作者：
P. Cassoux
中科院分区：
文献类型：
--
作者：
A. Sato;E. Ojima;H. Akutsu;Y. Nakazawa;H. Kobayashi;Hisashi Tanaka;A. Kobayashi;P. Cassoux
λ-（BETS）2（FexGa 1− x）Cl 4（x <$0.45）晶体在液氦温度附近经历连续的超导和超导到绝缘体的转变。在超导相中观察到了大的反磁化率（4K时为1.35 - 35 emu/mol）。4.7，在4.3 K下表现出超导转变，在3.7 K下表现出超导体到绝缘体的转变，可以被认为是超导体到绝缘体转变的体性质的证据。磁化率的各向异性和自旋翻转行为表明，该体系具有π-d耦合的反铁磁绝缘基态，这与λ-（BETS）2FeCl 4在8.5K时表现出的金属-绝缘体和反铁磁耦合相变基本相同.易磁化轴平行于c方向。与具有超导基态的富Ga（x< 0.35）系统不同，富Fe系统如λ-（BETS）2（Fe0.7Ga0.3）Cl 4在常压下表现出金属-绝缘体转变。然而，在高压下，π和d电子倾向于彼此独立，系统处于超导基态。
The crystal of λ-(BETS) 2 (F e x Ga 1− x) C l 4 with x≈ 0.45 undergoes successive superconducting and superconductor-to-insulator transitions around liquid helium temperature. The large diamagnetic susceptibility (≈-35 emu/mol at 4 K) observed in the superconducting phase of the system with x≈ 0. 4 7, which exhibits a superconducting transition at 4.3 K and superconductor-to-insulator transition at 3.7 K, can be regarded as evidence for the bulk nature of the superconductor-to-insulator transition. The anisotropy of the susceptibility and spin-flop behavior indicate that the system takes a π-d coupled antiferromagnetic insulating ground state, which is essentially the same as that of λ-(BETS) 2 FeCl 4 exhibiting a coupled metal-insulator and antiferromagnetic transition at 8.5 K. The easy axis is parallel to the c direction. Unlike the Ga-rich system (x< 0.35) with superconducting ground state, the Fe-rich system such as λ-(BETS) 2 (F e 0.7 Ga 0.3) C l 4 shows a metal-insulator transition at ambient pressure. At high pressure, however, the π and d electrons tend to be independent of each other and the system takes a superconducting ground state.