Despina Louca
· Maxine S. and Jesse W. Beams Professor of Physics Department ChairVerifiedUniversity of Virginia · Physics
Active 1993–2026
About
Despina Louca is the Maxine S. and Jesse W. Beams Professor of Physics and serves as the Department Chair at the University of Virginia. The provided page text does not include specific details about her research focus, background, or key contributions.
Research topics
- Crystallography
- Physics
- Chemistry
- Computer Science
- Quantum mechanics
- Condensed matter physics
- Materials science
- Chemical physics
- Thermodynamics
- Mathematics
- Nanotechnology
- Nuclear magnetic resonance
- Algorithm
Selected publications
Exchange anisotropy-driven noncollinear magnetism and magnetic transitions in MnTiO3 ilmenite
ArXiv.org · 2026-03-05
articleOpen accessSenior authorEvidence for multiple magnetic transitions and unconventional spin exchange interactions in the ilmenite insulator MnTiO3 is provided via neutron scattering. On cooling, while G-type antiferromagnetic (AFM) order sets in first at 63 K with a k1 = (000) characteristic wave vector, a weaker second magnetic transition with k2 = (00 3/2 ) appears near 42 K, giving rise to a noncollinear structure. Intrinsic buckling of the honeycomb lattice along c creates bond anisotropy and a distorted crystal field that can lead to exchange paths that modulate orbital overlap and spin-orbit coupling. The inelastic spectrum is best described by magnetic exchange anisotropy that breaks the local symmetry of the honeycomb, with competing AFM Heisenberg, Dzyaloshinskii-Moriya and alternate intra-planar ferromagnetic (FM) interactions, that may yield a weakly-coupled ladder system.
Exchange anisotropy-driven noncollinear magnetism and magnetic transitions in MnTiO3 ilmenite
Open MIND · 2026-03-05
preprintSenior authorEvidence for multiple magnetic transitions and unconventional spin exchange interactions in the ilmenite insulator MnTiO3 is provided via neutron scattering. On cooling, while G-type antiferromagnetic (AFM) order sets in first at 63 K with a k1 = (000) characteristic wave vector, a weaker second magnetic transition with k2 = (00 3/2 ) appears near 42 K, giving rise to a noncollinear structure. Intrinsic buckling of the honeycomb lattice along c creates bond anisotropy and a distorted crystal field that can lead to exchange paths that modulate orbital overlap and spin-orbit coupling. The inelastic spectrum is best described by magnetic exchange anisotropy that breaks the local symmetry of the honeycomb, with competing AFM Heisenberg, Dzyaloshinskii-Moriya and alternate intra-planar ferromagnetic (FM) interactions, that may yield a weakly-coupled ladder system.
Charge density wave and superconductivity modulated by c-axis stacking in the TaSe2 polytypes
Open MIND · 2026-02-12
preprintSenior authorThe layered transition metal dichalcogenide, TaSe2, exhibits rich electronic phenomena across its polymorphs, 1T, 2H, and 3R, largely driven by differences in atomic coordination and c-axis stacking. In the 1T phase, octahedral coordination and AA stacking promote strong interlayer coupling and stabilize a commensurate charge density wave (CDW) with star-of-David clusters that set in at high temperatures. The 2H phase exhibits trigonal prismatic coordination with AB stacking, and hosts both incommensurate and commensurate CDW phases and weak superconductivity at very low temperatures. The 3R phase, characterized by ABC stacking and trigonal prismatic coordination, exhibits enhanced superconductivity along with CDW order, attributed to modified interlayer hybridization and reduced CDW competition. These stacking-dependent variations in interlayer coupling are critical in tuning correlated states in the dichalcogenides.
Charge density wave and superconductivity modulated by c-axis stacking in the TaSe2 polytypes
ArXiv.org · 2026-02-12
articleOpen accessSenior authorThe layered transition metal dichalcogenide, TaSe2, exhibits rich electronic phenomena across its polymorphs, 1T, 2H, and 3R, largely driven by differences in atomic coordination and c-axis stacking. In the 1T phase, octahedral coordination and AA stacking promote strong interlayer coupling and stabilize a commensurate charge density wave (CDW) with star-of-David clusters that set in at high temperatures. The 2H phase exhibits trigonal prismatic coordination with AB stacking, and hosts both incommensurate and commensurate CDW phases and weak superconductivity at very low temperatures. The 3R phase, characterized by ABC stacking and trigonal prismatic coordination, exhibits enhanced superconductivity along with CDW order, attributed to modified interlayer hybridization and reduced CDW competition. These stacking-dependent variations in interlayer coupling are critical in tuning correlated states in the dichalcogenides.
Physical review. B./Physical review. B · 2026-01-13
articleSenior authorEnergy & environment materials · 2025-01-28 · 2 citations
articleOpen accessThermoelectric coolers utilizing the Peltier effect have dominated the field of solid‐state cooling but their efficiency is hindered by material limitations. Alternative routes based on the Thomson and Nernst effects offer new possibilities. Here, we present a comprehensive investigation of the thermoelectric properties of 1T‐TiSe 2 , focusing on these effects around the charge density wave transition (≈200 K). The abrupt Fermi surface reconstruction associated with this transition leads to an exceptional peak in the Thomson coefficient of 450 μV K −1 at 184 K, surpassing the Seebeck coefficient. Furthermore, 1T‐TiSe 2 exhibits a remarkably broad temperature range (170–400 K) with a Thomson coefficient exceeding 190 μV K −1 , a characteristic highly desirable for the development of practical Thomson coolers with extended operational ranges. Additionally, the Nernst coefficient exhibits an unusual temperature dependence, increasing with temperature in the normal phase, which we attribute to bipolar conduction effects. The combination of solid–solid pure electronic phase transition to a semimetallic phase with bipolar transport is identified as responsible for the unusual Nernst trend and the unusually large Thomson coefficient over a broad temperature range.
Applied Physics Letters · 2025-10-13
articlePhase change materials (PCMs) are well-known for their reversible and rapid switching between crystalline and amorphous phases through thermal excitations mediated by strong electrical or laser pulses. This crystal-to-amorphous transition is accompanied by a remarkable contrast in optical and electronic properties, making PCMs useful in nonvolatile data storage applications. Here, we combine electrical transport and angle resolved photoemission spectroscopy (ARPES) measurements to study the electronic structure of bulk Ge2Sb2Te5−5xSe5x (GSST) for 0≤x≤0.8, where x represents the amount of Se substituting Te in Ge2Sb2Te5—a prototypical PCM. The single-particle density of states (SDOS) derived from the integrated ARPES data display metallic behavior for all x, as evidenced by the presence of a finite density of states in the vicinity of the chemical potential. Transport measurements also display clear signatures of metallic transport, consistent with the SDOS data. The temperature dependence of the resistance indicates the onset of moderate electron–electron Coulomb interaction effects at low temperatures for x≥0.6. At the same time, the magnetoresistance data show signatures of weak antilocalization for x≥0.6. An analysis of the temperature dependence of the phase coherence length suggests that electron dephasing is primarily due to inelastic electron–electron scattering. We find that these effects are enhanced with increasing x, portraying GSST as a PCM with electronic interactions that can be tuned via chemical doping.
2025-06-01
reportOpen accessOak Ridge National Laboratory (ORNL) operates the world's two most powerful neutron sources: the High Flux Isotope Reactor (HFIR) and the Spallation Neutron Source (SNS).These form a national user facility that provides neutron scattering instruments to probe and image static and dynamic properties of materials down to the atomic scale.Because the neutron carries a magnetic moment and the energies and wavelengths of neutrons match energy and length scales associated with magnetic materials, these facilities provide unique sensitivity to magnetism.This report outlines a set of coordinated recommendations for new sample environments to transform magnetic field-enabled neutron scattering.It considers three classes of sample environment systems for the neutron scattering beam lines to transform the ability of scientists to understand and develop advanced electronic properties of materials through (1) ultra-high magnetic field neutron scattering, (2) neutron scattering in static field environments that can move from beamline to beamline, and (3) time-dependent magnetic field sample environments.It is the result of an engagement with the North American neutron scattering user community and expresses the participants' assessment of the opportunities for new science and materials innovation that would result from combining neutron scattering with static and pulsed magnetic fields.Three working groups were formed and led by members of the neutron scattering user community with support from ORNL instrument scientists.The first group examined the science enabled by the largest static magnetic fields, requiring fixed, dedicated installations.The second group examined the scientific opportunities from static magnetic field sample environments that can be moved between and operated on multiple instruments.The third group considered science enabled by time-dependent and pulsed magnetic field sample environments.The working groups met online during the spring, summer and fall of 2024.The report was edited during the Fall of 2024 through spring 2025.Starting with an executive summary, the report was written by the leaders and members of the working groups and by members of the neutron scattering division (NSD) who attended these meetings. 6.
Long-lived dynamics of the charge density wave in TiSe$_2$ observed by neutron scattering
ArXiv.org · 2025-09-18
preprintOpen accessTime-resolved elastic neutron scattering combined with rapid laser heating was used to probe the charge density wave (CDW) state in 1T-TiSe$_2$, capturing both the melting and reformation of the CDW on long timescales and providing clues on the roles of phonons and excitons. With the laser source on, superlattice Bragg peaks such as (-1.5, -1.5, 1.5) observed below the CDW transition due to the new lattice periodicity, dissipate within 5 seconds, at a rate that is much slower than the sample's thermal response to the heat wave propagation. Whereas the electronic ordering associated with the CDW phase is disrupted rapidly by the laser-induced heating, the periodic lattice distortion (PLD) exhibits a markedly slower evolution during the melting process. This delayed suppression of the PLD relative to the thermal response indicates that CDW melting proceeds through a nonthermal pathway, likely linked to the loss of superlattice phonons such as the soft mode at q = (0.5 ,0, 0.5 ).
Physical review. B./Physical review. B · 2025-01-23 · 3 citations
articleOpen accessSenior authorRecent observations of unconventional superconductivity (SC) in thin films of ${\mathrm{LaNiO}}_{2}$ (critical temperature ${T}_{\mathrm{c}}\ensuremath{\simeq}$ 10 K) and in bulk single crystals of ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$ under pressure ${T}_{\mathrm{c}}\ensuremath{\simeq}80\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ have cemented a long sought-after class of SC nickelates. In ${\mathrm{La}}_{1\ensuremath{-}x}\mathrm{Sr}{}_{x}{\mathrm{NiO}}_{2}$, SC appears only in films for reasons not understood. We perform a combination of experiments to probe the crystal structure and magnetic order in bulk ${\mathrm{LaNiO}}_{2}$ together with ab initio calculations of the electronic structure. We find that the infinite layers are naturally buckled out-of-plane. The electronic bands are largely unaffected by the buckling, but uniaxial compression along the $c$ axis may lead to a Lifshitz transition.
Recent grants
Amorphous Steels: Atomic Structure Characterization via Experiment and Modeling
NSF · $303k · 2008–2012
Disorder and Superconductivity: the relation of crystal structure and magnetism to superconductivity
NSF · $456k · 2014–2017
Symmetry, entanglement, and far-from equilibrium perturbations in 2D materials
NSF · $564k · 2022–2026
Frequent coauthors
- 35 shared
John Schneeloch
University of Virginia
- 25 shared
Daniel Phelan
Argonne National Laboratory
- 22 shared
T. Egami
Oak Ridge National Laboratory
- 21 shared
Junjie Yang
- 20 shared
Chunruo Duan
Rice University
- 20 shared
Peng Tong
Chinese Academy of Sciences
- 18 shared
Aaron Wegner
University of Arkansas at Fayetteville
- 18 shared
A. Llobet
Education
- 1997
Ph.D.
Pennsylvania
Awards & honors
- Anne Mayes Prize (2025)
- Fellow of the Neutron Scattering Society of America (2022)
- Distinguished Researcher Award (2021)
- President of the Neutron Scattering Society of America (2017…
- APS Fellow (2014)
- Resume-aware match score
- Save to shortlist
- AI-drafted outreach
See your match with Despina Louca
PhdFit ranks faculty by your research interests, methods, and publications — grounded in their actual work, not templates.
- Free to start
- No credit card
- 30-second signup