Low-dc-field susceptibility ofCuMnspin glass

Abstract

Low-dc-field magnetic-susceptibility measurements are reported for CuMn alloys containing 1.08-and 2.02-at.'/o Mn using a superconducting quantum-interference device. The zero-field cooled initial susceptibility shows a cusplike peak at T~, the transition temperature to a spin-glass state. After field cooling from T & T~( even for 0=2 6), the susceptibility belo~T~is nearly independent of temperature with the constant value of -0. 97X(T~). The high-temperature susceptibility follows a Curie-Weiss law until just above T~; the value of the Curie temperature is very small. Using the theory of Sherrington and Kirkpatrick, the spin-glass order parameter q(T) is extracted from the susceptibility data. A critical index P=1 is obtained assuming a power law for q(T)~(1 -T/T~)&. The results are qualitatively in agreement with the prediction of an Edwards-Anderson-type mean-field theory.

LiV2O4: A Heavy Fermion Transition Metal Oxide

“…which has the same V oxidation state as in LiV204, also displays a cusp in \°'^{R) at RS 33 K and x°^^(T) follows the Curie-Weiss law for r ~ 50K [31]. The susceptibilities of these V-0 phases are all on the order of lO""* to lO'^cm^mol at low T [31,122]. Moreover, the T variations of in these vanadium oxides for T ~ lOK are, upon decreasing T. decreasing (Vo-yOa) or nearly T independent (V'aOs and \'407).…”

“…A typical example is Mn-doped Cu ( Fig. 1.6) [31]. As temperature T decreases from above a transition temperature, namely, a spin glass temperature (or spin freezing temperature) T^.…”

Extended droplet theory for aging in short-range spin glasses and a numerical examination

“…A very important issue is then whether the two susceptibilities χ EA and χ FC are the same or different. As we noted in the introduction this is intimately related with the fundamental experimental observation in spin-glass systems 9 , namely χ FC > χ ZFC . One of the most remarkable finding of the dynamical mean-field theory 8 is that indeed an inequality χ FC > χ EA (16) holds with χ FC defined in (10) and χ EA defined in (15).…”

“…To check the linearity of the response, we examined the sum rule (9): the sum of the two susceptibilities become (T /J)χ ZF C (t, 0). As shown in Fig.12, the sum rule is satisfied over our time window within the statistical ac- curacy.…”

The out-of-equilibrium dynamics of the Sherrington–Kirkpatrick model

“…Figure 4 shows the χ ag (C) curve determined using the zfc data of Nagata et al for two concentrations [33]. There are no experimental points for C/q d > 0.8 that correspond to rather low temperatures.…”