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 (Jeff) 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 Ho2Ti2O7, and show that the magneto-chemical potential depends on the spin sublattice (α or β), 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 Jeff for the β-sublattice. Additional simulations, including next-nearest neighbor interactions (J2), 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 Jeff and the spin-spin interactions that contribute to it.
| Original language | English |
|---|---|
| Article number | 3818 |
| Journal | Nature Communications |
| Volume | 13 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2022 |
Funding
C.B. and K.B. acknowledge support from the National Research Foundation, under grant NSF DMR-1847887. J.N. and T.S. acknowledge support from the National Research Foundation, under grant NSF DMR-1606952. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement No. DMR-1157490, No. DMR-1644779, and the State of Florida. Q.H. acknowledges support from the National Research Foundation, under grant NSF-DMR-2003117. H.D.Z acknowledges support from the NHMFL Visiting Scientist Program, which is supported by NSF Cooperative Agreement No. DMR-1157490 and the State of Florida. H.J.C. acknowledges support from the National Research Foundation, under grant NSF DMR-2046570, and start-up funds from Florida State University and the National High Magnetic Field Laboratory. The simulations were performed on the Research Computing Cluster (RCC) and the Planck cluster at Florida State University. We thank R. Moessner and L. Jaubert for helpful discussions.