Absence of a T2/3 specific heat anomaly in a U(1) spin liquid with a large spinon Fermi surface

Abstract

Effective gauge theories based on slave particle construction are widely used to describe quantum number fractionalization in strongly correlated electron systems. However, even setting aside the debates on the confinement issue of the slave particles, there are still significant conflicts between theory and experiment. In particular, a ${T}^{2/3}$ specific heat anomaly has been predicted to be the smoking-gun signature of low-lying gauge fluctuation in a $U(1)$ spin liquid with a large spinon Fermi surface, which has, however, never been observed. Here we show that such an anomaly is actually an artifact of a Gaussian approximation and is absent when the no-double-occupancy constraint on the slave particles is strictly enforced. We also show that projective construction based on slave particle representation provides a unified understanding of the mechanism of spin fractionalization in one- and two-dimensional spin liquids.