Strongly enhanced thermal expansion of low-dimensional itinerant weak antiferromagnets near the quantum critical points

Abstract

The thermal expansion of low-dimensional itinerant antiferromagnetic metals is discussed along with the recent study on the magneto-volume effect by Takahashi and Nakano [J. Phys.: Condens. Matter 16, 4505 (2004)]. In this study, we find that the thermal volume expansion derived by Takahashi and Nakano shows a stronger enhancement of the T-linear slope of the thermal expansion coefficient proportional to y−1∕2 and ln(1∕y), respectively, for one-dimensional and two-dimensional (2D) systems than that of three dimensions as we approach the magnetic instability point (y→0), where y is the inverse of the reduced staggered magnetic susceptibility. On the other hand, the same coefficient for the conventional term by Moriya and Usami [Solid State Commun. 34, 95 (1980)] is suppressed proportional to 1∕ln(1∕y) for 2D systems. The present result suggests that the temperature dependence of low-dimensional weak antiferromagnets is generally dominated by the strongly enhanced T2-linear thermal expansion from the magnetic origin.