Superconductivity and Magnetoresistance Oscillations in Weakly Pressurized Quasi One-Dimensional Superconductor (DMET-TSeF)₂AuI₂

Abstract

Low-temperature magnetoresistance measurements were used to characterize the superconducting state and the electronic structure of the quasi one-dimensional salt (DMET-TSeF) 2 AuI 2. The measurements revealed an essential role of small pressure created by grease molding. The small pressure suppressed the resistance jumps so that the intrinsic properties of the salt were clearly observed. The upper critical fields were determined for all three principal crystallographic directions. In contrast to strain-free samples, slightly pressurized samples show clear angle-dependent magnetoresistance oscillations related to the Fermi surface topology, demonstrating close similarity to the (TMTSF) 2 X salts.

High Magnetic Fields: A Tool for Studying Electronic Properties of Layered Organic Metals

“…Because of the strongly suppressed electron transfer in the z direction in our materials, the terms with q > 1 can usually be neglected. Therefore, one should expect the resonances to be pronounced only at integer values p / q = N , , in agreement with the experiment. − ,− , On the other hand, it seems unlikely that the observation of the high-index resonances (for example, in (TMTSF) 2 ReO 4 , the features with N up to 21 are observed 86 ) can be attributed to the existence of such high-order interchain transfer terms.…”

“…Naughton et al 80,81 and Osada et al 82 were the first to report an anomalous decrease of magnetoresistance in the metallic state of (TMTSF) 2 ClO 4 at the Lebed magic angles (LMAs) satisfying the condition in eq 32. Later the same effect, but even more pronounced, was found in (TMTSF) 2 X with X ) PF 6 and ReO 4 under pressure [83][84][85][86] as well as in some other q1D conductors, for example, (DMET-TSeF) 2 X (X ) AuCl 2 , AuI 2 ) 87,88 and (BEDT-TTF)(TCNQ). 89 LMA resonances, though less pronounced, have also been found in several q2D materials containing both a Fermi cylinder and a Fermi sheet, κ-(BEDT-TTF) 2 -Cu(NCS) 2 , 90-92 R-(BETS) 2 TlHg(SeCN) 4 , 93 R-(BEDT-TTF) 2 NH 4 Hg(SCN) 4 , 94 and pressurized (to normal metallic state) R-(BEDT-TTF) 2 KHg(SCN) 4 .…”

“…Therefore, one should expect the resonances to be pronounced only at integer values p/q ) N, 113,114 in agreement with the experiment. [80][81][82][83][84][85][86][87][88][89][91][92][93][94][95]115 On the other hand, it seems unlikely that the observation of the high-index resonances (for example, in (TMTSF) 2 ReO 4 , the features with N up to 21 are observed 86 ) can be attributed to the existence of such high-order interchain transfer terms.…”

Multidimensional nature of molecular organic conductors revealed by angular magnetoresistance oscillations

“…The first experimental evidence of such effect features in magnetoresistance at certain magic angles was observed in the Bechgaard salt (TMTSF) 2 ClO 4 [5,6,7]. Similar effects have since been found in several other Q1D organic conductors, such as (TMTSF) 2 PF 6 [8,20], (TMTSF) 2 ReO 4 [21], (DMET-TSeF) 2 X (X=AuCl 2 , AuI 2 , I 3 ) [22,23,24], (DMET) 2 CuCl 2 [25],(BEDT-TTF) (TCNQ) [26], as well as in the material discussed here, (DMET) 2 I 3 [16].…”

Magic Angle Effects of One-Dimensional Axis Conductivity in Quasi-One-Dimensional Conductors

“…By studying the interaction of electrons with impurities as well as interaction between electrons Lebed and Bak [2] have predicted that the resistance, R xx , has peaks at the magic angles θ = tan −1 ( b c p q ), where p and q are mutually prime integers and b and c are lattice constants, when the magnetic field is rotated in the plane perpendicular to the most conducting a axis. Experimentally, dips, instead of peaks, of the resistance at the magic angles are observed in both R xx and R zz in various quasi-one-dimensional organic conductors, (TMTSF) 2 ClO 4 [3,4], (TMTSF) 2 PF 6 [5,6], (TMTSF) 2 ReO 4 [7], (DMET) 2 I 3 [8], (DMET) 2 CuCl 2 [9], (DMET-TSeF) 2 AuCl 2 [10] and (DMET-TSeF) 2 AuI 2 [10,11]. It is called as the magic angle effect(MAE).…”