59 citations · 625 across the 32 of their papers we have counts for
26 papers · 1 filter
Cascade of vestigial orders in two-component superconductors: nematic, ferromagnetic, s-wave charge-4e, and d-wave charge-4e states
Matthias Hecker, Roland Willa, Jörg Schmalian +1
Electronically ordered states that break multiple symmetries can melt in multiple stages, similarly to liquid crystals. In the partially-melted phases, known as vestigial phases, a…
3DSC - A New Dataset of Superconductors Including Crystal Structures
Timo Sommer, Roland Willa, Jörg Schmalian +1
Data-driven methods, in particular machine learning, can help to speed up the discovery of new materials by finding hidden patterns in existing data and using them to identify prom…
Interplay of stripe and double-Q magnetism with superconductivity in under the influence of magnetic fields
Kristin Willa, Roland Willa, Frederic Hardy +4
At undergoes a novel first-order transition from a four-fold symmetric double-Q magnetic phase to a t…
Identification of multiple-flux-quanta vortices by core states in the two-band superconductor Pb
Thomas Gozlinski, Qili Li, Rolf Heid +5
Superconductors are of type I or II depending on whether they form an Abrikosov vortex lattice. Although bulk lead (Pb) is classified as a prototypical type-I superconductor, we ob…
Hessian characterization of a vortex in a maze
Roland Willa, Vadim B. Geshkenbein, Gianni Blatter
Recent advances in vortex imaging allow for tracing the position of individual vortices with high resolution. Pushing an isolated vortex through the sample with the help of a contr…
Designing high-performance superconductors with nanoparticle inclusions: comparisons to strong pinning theory
Sarah C. Jones, Masashi Miura, Ryuji Yoshida +4
One of the most promising routes for achieving unprecedentedly high critical currents in superconductors is to incorporate dispersed, non-superconducting nanoparticles to control t…
A topological flux trap: Majorana bound states at screw dislocations
Stefan Rex, Roland Willa
The engineering of non-trivial topology in superconducting heterostructures is a very challenging task. Reducing the number of components in the system would facilitate the creatio…
Perspective: Challenges and Transformative Opportunities in Superconductor Vortex Physics
Serena Eley, Andreas Glatz, Roland Willa
In superconductors, the motion of vortices introduces unwanted dissipation that is disruptive to applications. Fortunately, material defects can immobilize vortices, acting as vort…
Inhomogeneous time-reversal symmetry breaking in
Roland Willa, Matthias Hecker, Rafael M. Fernandes +1
We show that the observed time-reversal symmetry breaking (TRSB) of the superconducting state in can be understood as originating from in…
Vortex-lattice melting and paramagnetic depairing in the nematic superconductor FeSe
F. Hardy, L. Doussoulin, T. Klein +9
The full H-T phase diagram in the nematic superconductor FeSe is mapped out using specific-heat and thermal-expansion measurements down to 0.7 K and up to 30 T for both field direc…
Vortex phases and glassy dynamics in the highly anisotropic superconductor HgBaCuO
Serena Eley, Roland Willa, Mun K. Chan +2
We present an extensive study of vortex dynamics in a high-quality single crystal of HgBaCuO (Hg1201), a highly anisotropic superconductor that is a model system for st…
Melting of vortex lattice in magnetic superconductor
A. E. Koshelev, K. Willa, R. Willa +6
The iron-based superconductors are characterized by strong fluctuations due to high transition temperatures and small coherence lengths. We investigate fluctuation behavior in the…
Thermal creep emerging from cooling a tilted vortex lattice in uniaxial superconductor
Roland Willa, Jose Augusto Galvis, Jose Benito-Llorens +3
A perturbed system relaxes towards an equilibrium given by a minimum in the potential energy landscape. This often occurs by thermally activated jumps over metastable states. The c…
Anisotropic upper critical field of pristine and proton-irradiated single crystals of the magnetically ordered superconductor RbEuFeAs
M. P. Smylie, A. E. Koshelev, K. Willa +12
We present a study of the upper critical field, H, of pristine and proton-irradiated RbEuFeAs crystals in pulsed magnetic fields of up to 65 T. The data for H…
Strong pinning theory of thermal vortex creep in type II superconductors
Martin Buchacek, Vadim B. Geshkenbein, Roland Willa +1
We study thermal effects on pinning and creep in type-II superconductors where vortices interact with a low density of strong point-like defects with pinning energy and…
Strongly fluctuating moments in the high-temperature magnetic superconductor RbEuFeAs
K. Willa, R. Willa, J. -K. Bao +5
We report detailed specific heat measurements on the recently discovered magnetic superconductor RbEuFeAs. We investigated the superconducting transition at 37K and extract…
Nanocalorimetric Evidence for Nematic Superconductivity in the Doped Topological Insulator SrBiSe
Kristin Willa, Roland Willa, Kok Wee Song +6
Spontaneous rotational-symmetry breaking in the superconducting state of doped has attracted significant attention as an indicator for topological supe…
Thermal hysteresis of the Campbell response as a probe for bulk pinscape spectroscopy
Roland Willa, Mariano Marziali Bermúdez, Gabriela Pasquini
In type-II superconductors, the macroscopic response of vortex matter to an external perturbation depends on the local interaction of flux lines with the pinning landscape (pinscap…
Peak effect due to competing vortex ground states in superconductors with large inclusions
Roland Willa, Alexei E. Koshelev, Ivan A. Sadovskyy +1
Superconductors can support large dissipation-free electrical currents only if vortex lines are effectively immobilized by material defects. Macroscopic critical currents depend on…
Thermal depinning and creep in strong pinning theory
Martin Buchacek, Roland Willa, Vadim B. Geshkenbein +1
Pinning and thermal creep determine the response of numerous systems containing superstructures, e.g., vortices in type II superconductors, domain walls in ferroics, or dislocation…
Accelerated vortex dynamics across the magnetic 3D-to-2D crossover in disordered superconductors
Serena Eley, Roland Willa, Masashi Miura +4
Disorder can have remarkably disparate consequences in superconductors, driving superconductor-insulator transitions in ultrathin films by localizing electron pairs and boosting th…
Strong-pinning regimes by spherical inclusions in anisotropic type-II superconductors
R. Willa, A. E. Koshelev, I. A. Sadovskyy +1
The current-carrying capacity of type-II superconductors is decisively determined by how well material defect structures can immobilize vortex lines. In order to gain deeper insigh…
Probing the pinning landscape in type-II superconductors via Campbell penetration depth
R. Willa, V. B. Geshkenbein, G. Blatter
Type-II superconductors owe their magnetic and transport properties to vortex pinning, the immobilization of flux quanta through material inhomogeneities or defects. Characterizing…
Campbell response in type II superconductors under strong pinning conditions
R. Willa, V. B. Geshkenbein, R. Prozorov +1
Measuring the magnetic response of a type II superconductor provides valuable information on the pinning landscape (pinscape) of the material. We use strong pinning theory to…