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

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 T 2 -linear thermal expansion from the magnetic origin.