Magnetic field-tuned quantum critical point inCeAuSb2

Abstract

Transport, magnetic, and thermal properties at high magnetic fields $(H)$ and low temperatures $(T)$ of the heavy-fermion compound ${\mathrm{CeAuSb}}_{2}$ are reported. At $H=0$ this layered system exhibits antiferromagnetic order below ${T}_{N}=6\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Applying $B$ along the interplane direction, leads to a continuous suppression of ${T}_{N}$ and a quantum critical point at ${H}_{c}\ensuremath{\simeq}5.4\phantom{\rule{0.3em}{0ex}}\mathrm{T}$. Although it exhibits Fermi-liquid behavior within the N\'eel phase, in the paramagnetic state the fluctuations associated with ${H}_{c}$ give rise to unconventional behavior in the resistivity (sublinear in $T$) and to a $T\phantom{\rule{0.2em}{0ex}}\mathrm{ln}\phantom{\rule{0.2em}{0ex}}T$ dependence in the magnetic contribution to the specific heat. For $H>{H}_{c}$ and low $T$ the electrical resistivity exhibits an unusual ${T}^{3}$ dependence.