arXiv subjects

Doug A. Bonn

Publications and source records attributed to Doug A. Bonn.

3 recordsLinked to original sources

arXiv2026

Quasiparticle interference in LiFeAs: Signature of inelastic tunneling through spin fluctuations

Quasiparticle interference (QPI) is a powerful tool to characterize the symmetry of the superconducting order parameter in unconventional superconductors, by mapping the spatial dependence of elastic tunneling of electrons between the tip of a scanning tunneling microscope and a sample. Here, we consider the influence of inelastic tunneling on quasi-particle interference, exemplarily for the iron-based superconductor LiFeAs. We clearly observe replica features in both experimental QPI maps and the dispersion extracted from QPI, which from comparison with theoretical model calculations can be attributed to inelastic tunneling. Analysis of the QPI dispersion shows that the inelastic mode that gives rise to these replica features exhibits a resonance between 8 and 10 meV. Comparison of the energy scale of the resonance energy estimated from QPI with inelastic neutron scattering indicates that the replica features arise from interaction with spin fluctuations.

cond-mat.supr-con↗

arXiv2024

Discovery of Superconductivity and Electron-Phonon Drag in the Non-Centrosymmetric Weyl Semimetal LaRhGe$_3$

We present an exploration of the effect of electron-phonon coupling and broken inversion symmetry on the electronic and thermal properties of the semimetal LaRhGe$_3$. Our transport measurements reveal evidence for electron-hole compensation at low temperatures, resulting in a large magnetoresistance of 3000% at 1.8 K and 14 T. The carrier concentration is on the order of $10^{21}\rm{/cm}^3$ with high carrier mobilities of $2000~\rm{cm}^2/\rm{Vs}$. When coupled to our theoretical demonstration of symmetry-protected $\textit{almost movable}$ Weyl nodal lines, we conclude that LaRhGe$_3$ supports a Weyl semimetallic state. We discover superconductivity in this compound with a $T_{\text c}$ of 0.39(1) K and $B_{\rm{c}}(0)$ of 2.2(1) mT, with evidence from specific heat and transverse-field muon spin relaxation. We find an exponential dependence in the normal state electrical resistivity below $\sim50$ K, while Seebeck coefficient and thermal conductivity measurements each reveal a prominent peak at low temperatures, indicative of strong electron-phonon interactions. To this end, we examine the temperature-dependent Raman spectra of LaRhGe$_3$ and find that the lifetime of the lowest energy $A_1$ phonon is dominated by phonon-electron scattering instead of anharmonic decay. We conclude that LaRhGe$_3$ has strong electron-phonon coupling in the normal state, while the superconductivity emerges from weak electron-phonon coupling. These results open up the investigation of electron-phonon interactions in the normal state of superconducting non-centrosymmetric Weyl semimetals.

cond-mat.supr-con↗

arXiv2023

Absence of Fermi surface reconstruction in pressure-driven overdoped YBCO

The evolution of the critical superconducting temperature and field, quantum oscillation frequencies and effective mass $m^{*}$ in underdoped YBa$_2$Cu$_3$O$_{7-δ}$ (YBCO) crystals ($p$ = 0.11, with $p$ the hole concentration per Cu atom) points to a partial suppression of the charge orders with increasing pressure up to 7 GPa, mimicking doping. Application of pressures up to 25 GPa pushes the sample to the overdoped side of the superconducting dome. Contrary to other cuprates, or to doping studies on YBCO, the frequency of the quantum oscillations measured in that pressure range do not support the picture of a Fermi-surface reconstruction in the overdoped regime, but possibly point to the existence of a new charge order.

cond-mat.supr-con↗