Anomalous specific heat behaviour in the quadrupolar Kondo system PrV2Al20

TL;DR

This study investigates the low-temperature specific heat of PrV₂Al₂₀, revealing double phase transitions and gapless modes linked to quadrupole and octupole ordering, highlighting complex electronic behavior in this Kondo system.

Contribution

The paper provides detailed specific heat measurements of PrV₂Al₂₀, demonstrating clear phase transitions and gapless excitations, advancing understanding of quadrupolar Kondo systems.

Findings

Double transitions at 0.75 K and 0.65 K observed.

Specific heat follows T^4 dependence below T*.

Transitions become sharper and shift higher with crystal quality.

Abstract

We have measured the specific heat of PrV$_2$Al$_{20}$ at very low temperatures, using high quality single crystals with the residual resistivity ratio ~ 20. The high-quality single crystals exhibit clear double transitions at $T_{\rm Q} =$ 0.75 K and $T^* =$ 0.65 K. These transitions are clearer and shift to higher temperature in higher quality single crystals. Besides, there was no hysteresis in those transitions in warming and cooling process of the heat capacity measurements. In the ordered state below $T^*$, the specific heat shows a $T^4$ dependence, indicating the gapless mode associated with the quadrupole and/or octupole ordering.