arXiv subjects

Lucia Steinke

Publications and source records attributed to Lucia Steinke.

7 recordsLinked to original sources

arXiv2025

The Future of the Correlated Electron Problem

A central problem in modern condensed matter physics is the understanding of materials with strong electron correlations. Despite extensive work, the essential physics of many of these systems is not understood and there is very little ability to make predictions in this class of materials. In this manuscript we share our personal views on the major open problems in the field of correlated electron systems. We discuss some possible routes to make progress in this rich and fascinating field. This manuscript is the result of the vigorous discussions and deliberations that took place at Johns Hopkins University during a three-day workshop January 27, 28, and 29, 2020 that brought together six senior scientists and 46 more junior scientists. Our hope, is that the topics we have presented will provide inspiration for others working in this field and motivation for the idea that significant progress can be made on very hard problems if we focus our collective energies.

cond-mat.str-el↗

arXiv2022

Developing compact tuning fork thermometers for sub-mK temperatures and high magnetic fields

There is a growing demand for experiments on calorimetric and thermal transport measurements at ultra-low temperatures below 1 mK and high magnetic fields up to 16 T. Particularly, milligram-sized solid samples are of great interest. We present the development of scalable thermometers based on quartz tuning fork resonators immersed in liquid 3He and adapt hydrodynamic models to provide an improved description of temperature dependence in the high viscosity regime between 1 and 10 mK. We demonstrate successful thermometer operation and discuss the feasibility of fast and compact thermal probes suitable for small samples.

physics.ins-det↗

arXiv2017

Emergence of superconductivity in the canonical heavy-electron metal YbRh2Si2

We report magnetic and calorimetric measurements down to T = 1 mK on the canonical heavy-electron metal YbRh2Si2. The data reveal the development of nuclear antiferromagnetic order slightly above 2 mK. The latter weakens the primary electronic antiferromagnetism, thereby paving the way for heavy-electron superconductivity below Tc = 2 mK. Our results demonstrate that superconductivity driven by quantum criticality is a general phenomenon.

cond-mat.str-el↗

arXiv2017

Unconventional Large Linear Magnetoresistance in Cu$_{2-x}$Te

We report a large linear magnetoresistance in Cu$_{2-x}$Te, reaching $Δρ/ρ(0)$ = 250\% at 2 K in a 9 T field. This is observed for samples with $x$ in the range 0.13 to 0.22, and the results are comparable to the effects observed in Ag$_2 X$ materials, although in this case the results appear for a much wider range of bulk carrier density. Examining the magnitude vs. crossover field from low-field quadratic to high-field linear behavior, we show that models based on classical transport behavior best explain the observed results. The effects are traced to misdirected currents due to topologically inverted behavior in this system, such that stable surface states provide the high mobility transport channels. The resistivity also crosses over to a $T^2$ dependence in the temperature range where the large linear MR appears, an indicator of electron-electron interaction effects within the surface states. Thus this is an example of a system in which these interactions dominate the low-temperature behavior of the surface states.

cond-mat.mtrl-sci↗

arXiv2015

CaMn$_2$Al$_{10}$: itinerant Mn magnetism on the verge of ferromagnetic order

We report the discovery of \CMA, a metal with strong magnetic anisotropy and moderate electronic correlations. Magnetization measurements find a Curie-Weiss moment of $0.83\,\mathrm{μ_B}$/Mn, significantly reduced from the Hund's rule value, and the magnetic entropy obtained from specific heat measurements is correspondingly small, only $\approx 9$ \% of $R \mathrm{ln}\,2$. These results imply that the Mn magnetism is highly itinerant, a conclusion supported by density functional theory calculations that find strong Mn-Al hybridization. Consistent with the layered nature of the crystal structure, the magnetic susceptibility $χ$ is anisotropic below 20 K, with a maximum ratio of $χ_{[010]}/χ_{[001]}\approx 3.5$. A strong power-law divergence $χ(T)\sim T^{-1.2}$ below 20 K implies incipient ferromagnetic order, and an Arrott plot analysis of the magnetization suggests a vanishingly low Curie temperature $T_C\sim 0$. Our experiments indicate that \CMA~is a rare example of a Mn-based weak itinerant magnet that is poised on the verge of ferromagnetic order.

cond-mat.str-el↗

arXiv2013

The role of hyperfine coupling in magnetic and quadrupolar ordering of Pr3Pd20Si6

We study the ternary clathrate Pr3Pd20Si6 in specific heat and AC-susceptibility measurements on a high-quality single crystal, distinguishing antiferromagnetic (AFM) and antiferroquadrupolar (AFQ) ordering on two sublattices of inequivalent Pr sites. The specific heat shows the direct involvement of nuclear spin degrees of freedom in the AFM ordering, which is well supported by our calculation of the hyperfine level scheme without adjustable parameters. Pr3Pd20Si6 is therefore one of the rare materials where the nuclear moments are involved in the formation of the magnetic ground state.

cond-mat.str-el↗

arXiv2010

Hartree simulations of coupled quantum Hall edge states in corner-overgrown heterostructures

The electronic states in a corner-overgrown bent GaAs/AlGaAs quantum well heterostructure are studied with numerical Hartree simulations. Transmission electron microscope pictures of the junction justify the sharp-corner assumption. In a tilted magnetic field both facets of the bent quantum well are brought to a quantum Hall (QH) state, and the corner hosts an unconventional hybrid system of two coupled counter-propagating quantum Hall edges and an additional one-dimensional accumulation wire. A subsystems model is introduced, whereby the total hybrid dispersion and wavefunctions are explained in terms of the constituent QH edge- and accumulation wire-subsystem dispersions and wavefunctions. At low magnetic fields, orthonormal basis wavefunctions of the hybrid system can be accurately estimated by projecting out the lowest bound state of the accumulation wire from the edge state wavefunctions. At high magnetic fields, the coupling between the three subsystems increases as a function of the applied magnetic field, in contrast to coplanar barrier-junctions of QH systems, leading to large anticrossing gaps between the subsystem dispersions. These results are discussed in terms of previously reported experimental data on bent quantum Hall systems.

cond-mat.mes-hall↗