Unusual Field-Insensitive Phase Transition and Kondo Behavior in SmTi$_2$Al$_{20}$

TL;DR

This study reports on the discovery of a field-insensitive phase transition and heavy fermion behavior in SmTi₂Al₂₀, highlighting unusual Kondo-like resistivity and magnetic ordering in a complex intermetallic compound.

Contribution

It reveals a novel field-insensitive phase transition and heavy fermion state in SmTi₂Al₂₀, with detailed analysis of its electronic and magnetic properties.

Findings

Kondo-like resistivity below 50 K

Field-insensitive phase transition at 6.5 K

Heavy fermion behavior with γ = 150 mJ/(K² mol)

Abstract

Magnetization, electrical resistivity and specific heat measurements were performed on high-quality single crystalline SmTi$_2$Al$_{20}$ (residual resistivity ratio $\sim$ 40) grown by Al self-flux method. A Kondo-like $\log T$ dependence in the resistivity is observed below 50 K. We discovered a field-insensitive phase transition at $T_{x}$ = 6.5 K and a field-insensitive heavy fermion behavior with the electronic specific heat coefficient $\gamma$ = 150 mJ/(K$^{2}$ mol). Specific heat analysis reveals that the ground state is a $\Gamma_{8}$ quartet state and the Sm magnetic dipole moment $m_{{\rm Sm}}$ ($\sim 0.5 \mu_{{\rm B}}$ at $T \simeq$ 0) orders below $T_{x}$ in spite of the field-insensitive behavior. Possible reasons for the field insensitiveness will be discussed.