Pseudogap in underdoped cuprate seen in longitudinal magnetoresistance

Abstract

We report the results of in-plane magnetotransport study of slightly underdoped cuprate La$_{1.85}$Sr$_{0.15}$CuO$_{4}$ (LSCO15) with Ni impurity. Increasing Ni content $y$ causes a sharp drop in longitudinal magnetoresistance (LMR) in LSCO15 to broaden and move towards higher temperatures. Temperature $T_{mLMR}(y)$ of this local maximum in LMR coincides with temperature $T_{dev}(y)$, below which ideal resistivity from the parallel-resistor model deviates from its $T^{2}$-dependence. A direct comparison with the hole doping evolution of pseudogap (PG) in La$_{2-x}$Sr$_{x}$CuO$_{4}$ (LSCO), possible through the mobile-carrier concentration extracted from the thermopower measurements, allows to equate both characteristic temperatures $T_{mLMR}\!\cong\!T_{dev}$ with PG opening temperature $T^{*}$. The rate of PG closing by magnetic field parallel to the CuO$_{2}$ plane, in measurements up to 9 T, is consistent with spin-paramagnetic effect in this configuration and yields PG closing field $B_{pc}$ close to the second critical field $B_{c2}$ predicted for superconducting gap with the help of Werthamer--Helfand--Hohenberg theory. The field anisotropy of $B_{pc}$ suggests that orbital degrees of freedom also play a role in PG formation.

Ni-Driven Evolution of Pseudogap and Superconducting Gap in Underdoped Cuprate

“…The above seems to be a reasonable explanation for the lack of systematic change in T str with y. More details can be found in Appendix D in [23].…”

“…In this study, we compare the Ni-driven evolution of energy scales in LSCO15 characteristic for sc state with those relevant to PG, the manifestation of which in longitudinal magnetoresistance (LMR) we have found recently [23]. The Ni-induced enhancement of the PG energy scale accompanying suppression of superconductivity was observed in Ni-substituted underdoped NdBa 2 Cu 3 O 6.8 [24].…”

“…The deposition was carried out for 15 min in flowing oxygen under a pressure of 300 mTorr and at substrate temperature of 760 • C. The standard Hall-bar structure was patterned by photolithography. More technological details are given elsewhere [23].…”

“…The peak at T str = 255 K, which is much higher than T max , indicates the structural transition and will be addressed further. However, we have shown very recently that taking Ioffe-Regel-Mott (IRM) limit into account reveals the existence of a weak yet visible feature in zero-field transport, which temperature T dev correlates very well with T max [23].…”

High-pressure synthesis of A-site ordered perovskite PbMn3(CrMn3)O12 with long-range antiferromagnetic ordering and a spin glass transition

“…39,40 For the cluster spin glass and canonical spin glass, the value of τ 0 ranges from 10 −7 to 10 −10 s and 10 −12 to 10 −13 s, respectively. 41,42 Therefore, we conclude that cluster spin glass should form in PbMn 3 CrMn 3 O 12 .…”