Experimental investigation of the origin of the crossover temperature in cuprate superconductors via dc magnetic susceptibility

Abstract

We investigate the cross-over temperature T * as a function of doping in (CaxLa1−x)(Ba1.75−xLa0.25+x)Cu3Oy, where the maximum Tc (T max c ) varies continuously by 30% between families (x) with minimal structural changes. T * is determined by DC-susceptibility measurements. We find that T * scales with the maximum Néel temperature T max N of each family. This result strongly supports a magnetic origin of T * , and indicates that three dimensional interactions play a role in its magnitude.PACS numbers: 74.25. Dw,74.25.Ha, Free electrons do not have high temperature crossovers such as a pseudogap (PG), spin gap (SG), or development of antiferromagnetic (AFM) correlations. In the cuprates all of these exist, yet the interactions that lead to them are not completely clear. Nevertheless, the crossovers occur at a temperature T * which is much higher than T c , and closer to the three dimensional (3D) ordering temperature of the parent compound in the AFM state. Therefore, it is speculated that T * emerges from AFM fluctuations, and that the cross-overs are intimately linked, namely, the interaction responsible for one might be responsible for all [1,2,3]. Therefore, it is crucial to test the possibility of correlations between T ⋆ of a particular system and its magnetic properties, such as the Néel temperature T N of the parent compound, or its constituents, the in-and out-of-plane Heisenberg coupling constant J and J ⊥ , respectively. This is the motivation of the work presented here. We provide experimental evidence that strongly supports a magnetic origin for T * . Moreover, we show that T * stems from 3D interactions, similar to the Néel order, involving both J and J ⊥ .We investigate the origin of the T ⋆ by studying its variations as a function of the compound's magnetic properties, where small chemical changes are an implicit parameter. The variations in the magnetic properties are achieved by using four different families of the (Ca x La 1−x )(Ba 1.75−x La 0.25+x )Cu 3 O y (CLBLCO) system, having the YBa 2 Cu 3 O y (YBCO) structure, with x = 0.1 . . . 0.4. The phase diagram of the CLBLCO families is shown in Fig. 1(a). T c was measured by resistivity [4], and the spin glass temperature T g [5] and T N [6] by muon spin relaxation. Despite the rich phase diagram, the different CLBLCO families have negligible structural differences. All compounds are tetragonal, and there is no oxygen chain ordering as in YBCO [4]. The hole concentration in the CuO 2 planes does not depend on x [7,8]. The difference in the unit cell parameters a and c/3 between the two extreme families (x = 0.1 and 0.4) is 1% [4]. Thus, variations in T max c due to variations in ionic radii are not relevant [9]. The level of disorder, as detected by Cu and Ca nuclear magnetic resonance, is also identical for the different families [8,10]. In fact, the only strong variation between families noticed at present is the in-plane oxygen buckling angle [11]. This property can modify the intraplane near-and next-nearneighbors hopping, or interplane hoppi...

Origin of the Pseudogap and Its Influence on Superconducting State

“…Therefore, the pseudogap is more likely AFM correlation originated, and seem to be not related to the SC pairing. This is well supported by the scaling of T * (characterizing of the pseudogap) with the Neel temperature T N [46]. We notice that the magnitude of gap below and above E f near the antinode is almost the same in the intermediate doping (x = 0.1 ∼ 0.15).…”

Adiabatic variation of the charge density wave phase diagram in the 123 cuprate (CaxLa1−x)(Ba1.75−xBluschke1, Yaari2, Schierle3 et al. 2019Phys. Rev. B14090View full textAdd to dashboardCite

“…The crystal structure of CLBLCO (depicted in Fig. 1a) is of the TCDW measured in this study for single crystals with x = 0.1 and x = 0.4 are compared with Tc extracted from resistivity measurements, 21 T * from magnetization measurements 22 which are in agreement with measurements of the Knight shift, 23 and Tg and TN both obtained from muon spin resonance. 21,24 The solid black and red curves are parabolic fits to the TCDW data sets for the x = 0.1 and x = 0.4 families respectively.…”

“…Similarly the half occupation of the oxygen sites in the charge reservoir layer are indicated by half-red/white spheres, as opposed to the fully occupied oxygen sites (fully red spheres) in the CuO2 planes and at the apical sites. (b)TCDW measured in this study for single crystals with x = 0.1 and x = 0.4 are compared with Tc extracted from resistivity measurements, 21 T * from magnetization measurements22 which are in agreement with measurements of the Knight shift,23 and Tg and TN both obtained from muon spin resonance 21,24. The solid black and red curves are parabolic fits to the TCDW data sets for the x = 0.1 and x = 0.4 families respectively.…”

Critical-doping universality for cuprate superconductors: Oxygen nuclear-magnetic-resonance investigation of(CaxLa1−x)Amit1, Keren2 2010Phys. Rev. BSelf Cite161330View full textAdd to dashboardCite

“…1(b). The scaling procedure is somewhat different from that in previous works where the stretching was done around the oxygen density of T max c and a different set of Ks was used [7,[14][15][16]. Multiplying all the Ks by a numerical factor would yield equally good data collapse.…”