Ultra spin liquid in $\rm Lu_3Cu_2Sb_3O_{14}$

TL;DR

This paper investigates the thermodynamic properties of the ultra spin liquid in CuSbO, revealing universal scaling behavior similar to heavy fermion metals and quantum magnets, indicating a strongly correlated spin liquid state.

Contribution

It demonstrates that the ultra spin liquid in CuSbO exhibits universal thermodynamic scaling akin to heavy fermion systems and quantum magnets, highlighting a strongly correlated spin liquid nature.

Findings

Heat capacity behavior similar to heavy fermion RhSi

Spinon effective mass shows universal scaling

Thermodynamics dominated by strongly correlated spin liquid

Abstract

We analyze measurements of $C_{\rm mag}/T$, specific heat $C_{\rm mag}$ divided by temperature $T$, of the recently observed ultra spin liquid. The measurements are carried out in magnetic fields on the triangular lattice compound $\rm Lu_3Cu_2Sb_3O_{14}$. We show that the obtained heat capacity $C_{\rm mag}/T$ formed by ultra spin liquid as a function of temperature $T$ versus magnetic field $B$ behaves very similar to the electronic specific heat $C_{el}/T$ of the heavy fermion (HF) metal $\rm YbRh_2Si_2$ and that of the quantum magnet $\rm ZnCu_3(OH)_6Cl_2$. We further demonstrate that the spinon effective mass $M^*\propto C_{\rm mag}/T$ exhibits the universal scaling coinciding with that observed in HF metals and in $\rm ZnCu_3(OH)_6Cl_2$. Based on these observations we conclude that a strongly correlated spin liquid determines the thermodynamic properties of the ultra spin liquid of $\rm Lu_3Cu_2Sb_3O_{14}$.