arXiv subjects

Xueling Cui

Publications and source records attributed to Xueling Cui.

3 recordsLinked to original sources

arXiv2026

Ising Supercriticality and Universal Magnetocalorics in Spiral Antiferromagnet Nd$_3$BWO$_9$

The celebrated analogy between the pressure-temperature phase diagram of a liquid-gas system and the field-temperature phase diagram of a ferromagnet has long been a cornerstone for understanding universality of phase transitions and critical phenomena. Here we extend this analogy to a highly frustrated antiferromagnet, the spiral Ising compound Nd$_3$BWO$_9$ with kagome layers. In its phase diagram, we identify a metamagnetic transition line with a critical endpoint (CEP) located at $\mu_0H_{\mathrm{c}} \simeq 1.04$ T and $T_{\mathrm{c}} \simeq 0.3$ K. Above the CEP, an Ising supercritical regime emerges with crossover lines that follow a universal scaling law, as evidenced by the specific heat, magnetic susceptibility, and magnetocaloric measurements. Remarkably, we observe highly sensitive magnetic cooling near the emergent CEP, characterized by a divergent magnetic Gr\"uneisen ratio $\Gamma_H \propto 1/t^{\beta+\gamma-1}$, with $\beta + \gamma \simeq 1.563$ the sum of critical exponents of the 3D Ising universality class and $t \equiv (T-T_{\rm c})/T_{\rm c}$ the reduced temperature. Adiabatic demagnetization from 2 K and 4 T reaches a minimum temperature of 195 mK, via a self-cascading process that combines supercritical and topological cooling. Our findings open a new avenue for studying supercritical phenomena and magnetic refrigeration with the frustrated rare-earth compounds RE$_3$BWO$_9$ and, more broadly, in Ising-anisotropic antiferromagnets such as spin ices.

cond-mat.str-el↗

arXiv2025

Antiferromagnetic ordering and critical behavior induced giant magnetocaloric effect in distorted kagome lattice Gd$_3$BWO$_9$

We synthesize the high-quality Gd$_3$BWO$_9$ single crystal and investigate its lowtemperature magnetic and thermodynamic properties. Below $T\rm_{N}$ = 1.08 K, the anisotropic behavior of magnetic susceptibilities reveals that the Gd$^{3+}$ moments exhibit the dominant antiferromagnetic coupling along the $c$-axis, while displaying a ferromagnetic arrangement in kagome plane. With pronounced magnetic frustration, in adiabatic demagnetization refrigeration experiments starting from initial conditions of 9 T and 2 K, Gd$_3$BWO$_9$ polycrystal reaches a minimum temperature of 0.151 K, significantly lower than its $T\rm_{N}$. Due to the high density of Gd$^{3+}$ ions ($S$=7/2), the maximum magnetic entropy change reaches over 50 J kg$^{-1}$ K$^{-1}$ under fields up to 7 T in Gd$_3$BWO$_9$, nearly 1.5 times as large as commercial sub-Kelvin magnetic coolant Gd$_3$Ga$_5$O$_{12}$(GGG). The H-T phase diagram of Gd$_3$BWO$_9$ under $H$//$c$ exhibits field-induced critical behavior near the phase boundaries. This observation aligns with the theoretical scenario in which a quantum critical point acts as the endpoint of a line of classical second-order phase transitions. Such behavior suggests the importance of further investigations into the divergence of magnetic Gr\"uneisen parameter in the vicinity of critical field at ultralow temperatures.

cond-mat.str-el↗

arXiv2025

3D XY Universality and Nonlinear magnetic susceptibility in a kagome ice compound

Kagome spin ice is an intriguing class of spin systems constituted by in-plane Ising spins with ferromagnetic interaction residing on the kagome lattice, theoretically predicted to host a plethora of magnetic transitions and excitations. In particular, different variants of kagome spin ice models can exhibit different sequences of symmetry breaking upon cooling from the paramagnetic to the fully ordered ground state. Recently, it has been demonstrated that the frustrated intermetallic HoAgGe stands as a faithful solid-state realization of kagome spin ice. Here we use single crystal neutron diffuse scattering to map the spin ordering of HoAgGe at various temperatures more accurately and surprisingly find that the ordering sequence appears to be different from previously known scenarios: From the paramagnetic state, the system first enters a partially ordered state with fluctuating magnetic charges, in contrast to a charge-ordered paramagnetic phase before reaching the fully ordered state. Through state-of-the-art Monte Carlo simulations and scaling analyses using a quasi-2D model for the distorted Kagome spin ice in HoAgGe, we elucidate a single three-dimensional (3D) XY phase transition into the ground state with broken time-reversal symmetry (TRS). However, the 3D XY transition has a long crossover tail before the fluctuating magnetic charges fully order. More interestingly, we find both experimentally and theoretically that the TRS breaking phase of HoAgGe features an unusual, hysteretic response: In spite of their vanishing magnetization, the two time-reversal partners are distinguished and selected by a nonlinear magnetic susceptibility tied to the kagome ice rule. Our discovery not only unveils a new symmetry breaking hierarchy of kagome spin ice, but also demonstrates the potential of TRS-breaking frustrated spin systems for information technology applications.

cond-mat.str-el↗