Low-temperature spin dynamics and absence of magnetic order in layered $\alpha$-RuI$_3$
(2024)
Demonstration of Controlled Skyrmion Injection Across a Thickness Step
Nano Letters American Chemical Society (ACS) (2024)
Dichotomous dynamics of magnetic monopole fluids.
Proceedings of the National Academy of Sciences of the United States of America Proceedings of the National Academy of Sciences 121:21 (2024) e2320384121-e2320384121
Abstract:
A recent advance in the study of emergent magnetic monopoles was the discovery that monopole motion is restricted to dynamical fractal trajectories [J. N. Hallén <i>et al.</i>, <i>Science</i> <b>378</b>, 1218 (2022)], thus explaining the characteristics of magnetic monopole noise spectra [R. Dusad <i>et al., Nature</i> <b>571</b>, 234 (2019); A. M. Samarakoon <i>et al.</i>, <i>Proc. Natl. Acad. Sci. U.S.A.</i> <b>119</b>, e2117453119 (2022)]. Here, we apply this novel theory to explore the dynamics of field-driven monopole currents, finding them composed of two quite distinct transport processes: initially swift fractal rearrangements of local monopole configurations followed by conventional monopole diffusion. This theory also predicts a characteristic frequency dependence of the dissipative loss angle for AC field-driven currents. To explore these novel perspectives on monopole transport, we introduce simultaneous monopole current control and measurement techniques using SQUID-based monopole current sensors. For the canonical material Dy<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub>, we measure [Formula: see text], the time dependence of magnetic flux threading the sample when a net monopole current [Formula: see text] is generated by applying an external magnetic field [Formula: see text] These experiments find a sharp dichotomy of monopole currents, separated by their distinct relaxation time constants before and after <i>t</i> ~[Formula: see text] from monopole current initiation. Application of sinusoidal magnetic fields [Formula: see text] generates oscillating monopole currents whose loss angle [Formula: see text] exhibits a characteristic transition at frequency [Formula: see text] over the same temperature range. Finally, the magnetic noise power is also dichotomic, diminishing sharply after <i>t</i> ~[Formula: see text]. This complex phenomenology represents an unprecedented form of dynamical heterogeneity generated by the interplay of fractionalization and local spin configurational symmetry.Field-orientation-dependent magnetic phases in GdRu$_2$Si$_2$ probed with muon-spin spectroscopy
(2024)
Magnetostriction-driven muon localization in an antiferromagnetic oxide
Physical Review Letters American Physical Society 132:4 (2024) 046701