arXiv subjects

Fabian Hotz

Publications and source records attributed to Fabian Hotz.

3 recordsLinked to original sources

arXiv2024

Anharmonic quantum muon effects of light particles in a spin liquid material

The quantum behavior of light nuclei and other particles in materials challenges classical intuition and introduces novel phenomena. Here we demonstrate that muon spin spectroscopy ( $\mu$SR) is a powerful tool for exploring the quantum effects of light particles, such as the muon, in condensed matter. The muon's quantum nature is profoundly influenced by the surrounding, offering a unique probe for understanding the role of light atoms and their role in shaping local electronic environments. In Zn-barlowite, a candidate quantum spin liquid, we show that standard density functional theory (DFT) methods, which treat the muon as a classical point-like particle, fail to capture its strong quantum anharmonic effects. Only by modeling the muon as a spatially extended quantum particle, thus accounting for the anharmonicity, can the experimental $\mu$SR data be understood. This approach not only improves the interpretation of $\mu$SR results but also opens the door to studying the quantum effects of other light particles, like hydrogen and lithium nuclei, which can greatly influence material properties.

cond-mat.str-el↗

arXiv2022

Two types of charge order in the superconducting kagome material CsV$_3$Sb$_5$

The kagome metals of the family $A$V$_3$Sb$_5$, featuring a unique structural motif, harbor an array of intriguing phenomena such as chiral charge order and superconductivity. CsV$_3$Sb$_5$ is of particular interest because it displays a double superconducting dome in the region of the temperature-pressure phase diagram where charge order is still present. However, the microscopic origin of such an unusual behavior remains an unsolved issue. Here, to address it, we combine high-pressure, low-temperature muon spin relaxation with first-principles calculations. We observe a pressure-induced threefold enhancement of the superfluid density, which also displays a double peak feature, similar to the superconducting critical temperature. This leads to three distinct regions in the phase diagram, each of which features distinct slopes of the linear relation between superfluid density and the critical temperature. These results are attributed to a possible evolution of the charge order pattern from the superimposed tri-hexagonal Star-of-David phase at low pressures (within the first dome) to the staggered tri-hexagonal phase at intermediate pressures (between the first and second domes). Our findings suggest a change in the nature of the charge ordered state across the phase diagram of CsV$_3$Sb$_5$, with varying degrees of competition with superconductivity.

cond-mat.supr-con↗

arXiv2019

An exactly soluble model for a fractionalized Weyl semimetal

We construct an exactly solvable lattice model of a fractional Weyl semimetal (FWS). The low energy theory of this strongly interacting state is that of a Weyl semimetal built out of fractionally charged fermions. We show the existence of a universally quantized and fractional circular photogalvanic effect (CPGE) and a violation of the Wiedemann-Franz law in the system. Together with a spectral gap in the single-particle electronic Green's function they provide strong experimental signatures for this exotic gapless state of matter.

cond-mat.str-el↗