Investigation of the monopole magneto-chemical potential in spin ices using capacitive torque magnetometry

Abstract

The single-ion anisotropy and magnetic interactions in spin-ice systems give rise to unusual non-collinear spin textures, such as Pauling states and magnetic monopoles. The effective spin correlation strength ($J_{eff}$) determines the relative energies of the different spin-ice states. With this work, we display the capability of capacitive torque magnetometry in characterizing the magneto-chemical potential associated with monopole formation. We build a magnetic phase diagram of Ho${}_2$Ti${}_2$O${}_7$, and show that the magneto-chemical potential depends on the spin-sublattice ($\alpha$ or $\beta$), i.e., the Pauling state, involved in the transition. Monte-Carlo simulations using the dipolar-spin-ice Hamiltonian support our findings of a sublattice-dependent magneto-chemical potential, but the model underestimates the $J_{eff}$ for the $\beta$-sublattice. Additional simulations, including next-nearest neighbor interactions ($J_2$), show that long-range exchange terms in the Hamiltonian are needed to describe the measurements. This demonstrates that torque magnetometry provides a sensitive test for $J_{eff}$ and the spin-spin interactions that contribute to it.

Main text: 12 pages, 5 figures, 1 table; Supplemental Materials: 12 pages, 7 figures, 6 tables

References in corpus (7)

• Pinch Points and Kasteleyn Transitions: How Spin Ice Changes its Entropy
• Magnetization process of spin ice in a [111] magnetic field
• Sleuthing out exotic quantum spin liquidity in the pyrochlore magnet Ce${}_2$Zr${}_2$O${}_7$
• Intermediate magnetisation state and competing orders in Dy${}_2$Ti${}_2$O${}_7$ and Ho${}_2$Ti${}_2$O${}_7$
• First order metamagnetic transition in Ho2Ti2O7 observed by vibrating coil magnetometry at milli-Kelvin temperatures
• Ultrasonic investigations of spin-ices Dy${}_2$Ti${}_2$O${}_7$ and Ho${}_2$Ti${}_2$O${}_7$ in and out of equilibrium
• Magnetization beyond the Ising limit of Ho${}_2$Ti${}_2$O${}_7$

Cited by in corpus (4)

• Thermodynamics of the dipole-octupole pyrochlore magnet Ce${}_2$Hf${}_2$O${}_7$ in applied magnetic fields
• Origin and stability of generalized Wigner crystallinity in triangular moiré systems
• Proximal quantum control of spin and spin ensemble with highly localized control field from skyrmions
• Probing ice-rule-breaking transition in $\mathrm{D}{\mathrm{y}}_2\mathrm{T}{\mathrm{i}}_2{\mathrm{O}}_7$ thin film by proximitized transport and magnetic torque