About

Ian R. Fisher is a Humanities and Sciences Professor, Professor and Chair of Applied Physics, and Professor, by courtesy, of Materials Science and Engineering at Stanford University. His research group is based in the Geballe Laboratory for Advanced Materials at Stanford, where they study materials with unconventional magnetic and electronic properties. The broad aim of his research is to obtain a deeper understanding of the many effects that can emerge from electron correlation. His team employs techniques to grow high-quality single crystals of materials of interest and conducts experiments to probe the thermodynamic and transport properties of these materials, often in high magnetic fields. Current research interests include superconductivity, electronic nematic order, aspects of quantum magnetism, and the behavior of electrons in low-dimensional materials.

Research topics

• Quantum mechanics
• Physics
• Condensed matter physics
• Statistical physics
• Theoretical physics
• Optics

Selected publications

• Data from: Discovery of spontaneous mesoscopic strain waves in nematic domains using dark-field X-ray microscopy

  DRYAD · 2026-02-25

  datasetOpen accessSenior author

  Electronic nematic order arises when correlated electrons spontaneously break the rotational symmetry of a crystal lattice. When electronic nematic order couples bilinearly to symmetry-breaking lattice strain, both appear together at a single ferroelastic phase transition, producing structural twin domains with distinct orientations of the nematic director. While the effects of applied strain on these domains are well established, the intrinsic behavior of spontaneous subdomain strain fields has remained unexplored. Here, we report the discovery of spontaneous mesoscopic strain waves within individual nematic domains of an iron-based superconductor, observed using dark-field X-ray microscopy (DFXM). Using this novel full-field imaging technique, we visualize subdomain strain modulations emerging concurrently with nematic order. Elastic compatibility relations governing inhomogeneous strains provide a natural mechanism for the strain waves. Our findings reveal a broadly relevant form of strain self-organization and position DFXM as a powerful probe of the local interplay between lattice strain and electronic order.

  PublisherDOI

• Discovery of spontaneous mesoscopic strain waves in nematic domains using dark-field x-ray microscopy

  Science Advances · 2026-05-20

  articleOpen accessSenior authorCorresponding

  Electronic nematic order arises when correlated electrons spontaneously break the rotational symmetry of a crystal lattice. When electronic nematic order couples bilinearly to symmetry-breaking lattice strain, both appear together at a single ferroelastic phase transition, producing structural twin domains with distinct orientations of the nematic director. While the effects of applied strain on these domains are well established, the intrinsic behavior of spontaneous subdomain strain fields has remained unexplored. Here, we report the discovery of spontaneous mesoscopic strain waves within individual nematic domains of an iron-based superconductor, observed using dark-field x-ray microscopy (DFXM). Using this advanced full-field imaging technique, we visualize subdomain strain modulations emerging concurrently with nematic order. Elastic compatibility relations governing inhomogeneous strains provide a natural mechanism for the strain waves. Our findings reveal a broadly relevant form of strain self-organization and position DFXM as a powerful probe of the local interplay between lattice strain and electronic order.

  PublisherDOI

• Giant elastocaloric cooling at cryogenic temperatures in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mrow><mml:mi>Tm</mml:mi><mml:mi>VO</mml:mi></mml:mrow><mml:mn>4</mml:mn></mml:msub></mml:math> via a load-unload strain technique

  Physical Review Applied · 2025-01-31 · 3 citations

  articleSenior author

  Elastocaloric cooling holds considerable promise as a compact, quick alternative to standard cryogenic refrigeration, though its practical implementation still requires considerable research on candidate materials and appropriate techniques for applying large, rapid strains at low temperatures. In this study a load-unload approach is used to induce substantial strains in a candidate cryogenic elastocaloric working material, TmVO${}_{4}$, at low temperatures. Employing this technique, the authors observe a giant elastocaloric response, cooling the material by 2.3 K at a bath temperature of 5 K. These results provide a starting point for practical elastocaloric cooling in the subkelvin regime.

  PublisherDOI

• Time Resolved Core Level Spectroscopy Reveals Light-Induced Structural Changes in Gdte3

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Signatures of Fluctuation-Driven Magnetic Topological Charge in Pt-Ferromagnetic Insulator Bilayers

  Physical Review Letters · 2025-07-14

  article

  Chiral magnetic textures are of fundamental interest for studying exotic spin behavior, but also promising for the development of energy-efficient memory and logic devices. Recent computational work has suggested that in contrast to well-studied static chiral textures like skyrmions, there exists dynamic fluctuation-driven magnetic chirality even in the absence of long-range magnetic order. Here, we present definitive magnetotransport signatures of fluctuation-driven chirality in a model material system of Pt/Li_{0.5}Al_{1.0}Fe_{1.5}O_{4} (LAFO) bilayers, where LAFO is a ferromagnetic insulator. We establish a fluctuation-driven origin for the magnetic chirality by observing a strong correlation between the onset of the topological Hall effect and the destruction of magnetic order. Corroborated by Monte Carlo simulations, we develop a rigorous analytical framework to gain a first-principles understanding of scaling behaviors in the transport data. Our results bring novel insights to fluctuation-driven chirality and analysis of magnetotransport data.

  PublisherDOI

• Dynamical Scaling Reveals Topological Defects and Anomalous Evolution of a Photoinduced Phase Transition

  Physical Review X · 2025-08-28 · 1 citations

  articleOpen access

  Nonequilibrium states of quantum materials can exhibit exotic properties and enable unprecedented functionality and applications. These transient states are inherently inhomogeneous, characterized by the formation of topologically protected structures, requiring nanometer spatial resolution on femtosecond timescales to resolve their evolution. Using ultrafast total x-ray scattering at a free electron laser and a sophisticated scaling analysis, we gain unique access to the dynamics on the relevant mesoscopic length scales. Our results provide direct evidence that ultrafast excitation of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mrow><a:mi>LaTe</a:mi></a:mrow><a:mrow><a:mn>3</a:mn></a:mrow></a:msub></a:mrow></a:math> leads to formation of topological vortex strings of the charge density wave. These dislocations of the charge density wave exhibit anomalous, subdiffusive dynamics, slowing the equilibration process, providing rare insight into the nonequilibrium mesoscopic response in a quantum material. Our findings establish a general framework to investigate properties of topological defects, which are expected to be ubiquitous in nonequilibrium phase transitions and may arrest equilibration and enhance competing orders.

  PublisherOA PDFDOI

• Measurement of the dynamic charge susceptibility near the charge density wave transition in ErTe ₃

  Proceedings of the National Academy of Sciences · 2025-06-20

  articleOpen access

  A charge density wave (CDW) is a phase of matter characterized by a periodic modulation of valence electron density coupled with lattice distortion. Its formation is closely tied to the dynamical charge susceptibility, [Formula: see text], which reflects the collective electron dynamics of the material. Despite decades of study, [Formula: see text] near a CDW transition has never been measured at nonzero momentum, [Formula: see text], with meV energy resolution. Here, we investigate the canonical CDW transition in ErTe[Formula: see text] using momentum-resolved electron energy loss spectroscopy, a technique uniquely sensitive to valence band charge excitations. Unlike phonons, which soften via the Kohn anomaly, we find the electronic excitations exhibit purely relaxational dynamics well described by a diffusive model, with the diffusivity peaking just below the critical temperature, [Formula: see text]. Additionally, we report for the first time a divergence in the real part of [Formula: see text] in the static limit ([Formula: see text]), a long-predicted hallmark of CDWs. Unexpectedly, this divergence occurs as [Formula: see text], with only a weak thermodynamic signature at [Formula: see text]. Our study necessitates a reexamination of the traditional description of CDW formation in quantum materials.

  PublisherDOI

• The UK nationwide observational study of colon capsule: CAP ACCESS study

  Digestive and Liver Disease · 2025-05-13 · 1 citations

  articleOpen access

  BACKGROUND: Colon capsule endoscopy (CCE) is increasingly used as an alternative to optical endoscopy (OE), particularly in Europe. However, challenges like low completion rates, inadequate bowel preparation, high conversion to OE, and discrepancies in findings remain. Accurate polyp size measurement in CCE is essential to avoid unnecessary procedures due to size overestimation. OBJECTIVE(S): This retrospective study analysed real-world data to compare polyp size measurements between CCE, OE, and histopathology (HP) and assess the impact on the need for further procedures. METHODS: Data from 2508 participants across 12 UK centres were analysed, with 4898 polyps identified via CCE. Polyps were matched with OE and HP reports based on size, location, morphology, sequence, and count, including those meeting ≥3 criteria. Regional data from Scotland and England were compared. RESULTS: Half of the CCE patients required follow-up OE, with 29 % undergoing colonoscopy. Among these, 32 % required OE for polypectomy, and 18 % due to incomplete CCE. In these cases, CCE overestimated polyp size by an average of 2.5 mm compared to HP and 2.7 mm compared to OE, leading to 17.3 % of potentially deferrable procedures. CONCLUSION: one in six participants had a further procedure reflecting the overestimation of polyp size. AI advancement could enhance polyp measurement accuracy and reduce unnecessary procedures whilst improving the cost-effectiveness of CCE.

  PublisherOA PDFDOI

• Time Resolved Core Level Spectroscopy Reveals Light-Induced Structural Changes in Gdte3

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Dimensionality reduction of optically generated vortex strings in a charge density wave

  ArXiv.org · 2025-09-11

  preprintOpen access

  In phase transitions, mesoscale structures such as topological defects, vortex strings, and domain walls control the path towards equilibrium, and thus the functional properties of many active devices. In photoinduced phase transitions driven by femtosecond laser excitation, the temporal (pulse duration) and spatial (penetration depth) structure of the optical excitation present opportunities for control and creating structures with unique topologies. By performing time-resolved optical pump, x-ray probe experiments on the CDW system Pd-intercalated ErTe$_{3}$, we gain access to the nanoscale dynamics of the mesoscale topological features (vortex strings) produced after a quench, which have a different apparent dimensionality than the topological defects predicted from the bulk system. We show that these vortex strings persist for much longer than the electronic recovery time. The critical exponent obtained from power-law scaling of the intensity as a function of wavevector shows a reduction in the effective dimensionality of the topological defects in the system, corroborated by time-dependent Ginzburg-Landau simulations. Our results demonstrate a novel pathway to use light to control the dimensionality and orientation of topological defects in quantum materials, which could be used to stabilize competing quantum states.

  PublisherOA PDFDOI

Recent grants

• New Materials for Quantum Magnetism: Spin Dimer Compounds

  NSF · $350k · 2007–2010

• EAGER: CRYO: Development of materials and techniques to enable sub-Kelvin cooling via adiabatic decompression of para-nematic materials.

  NSF · $300k · 2022–2024

• Ground States of Disordered Quantum Magnets

  NSF · $365k · 2012–2016

• CAREER: New Materials in Condensed Matter Physics - The Case of Quasicrystals

  NSF · $455k · 2002–2007

Frequent coauthors

• James G. Analytis

  253 shared

• P. C. Canfield

  201 shared

• Jiun‐Haw Chu

  University of Washington

  189 shared

• Zhi‐Xun Shen

  Stanford University

  170 shared

• Joshua Straquadine

  Stanford University

  112 shared

• Hsueh-Hui Kuo

  SLAC National Accelerator Laboratory

  81 shared

• Dong-Hui Lu

  Stanford Synchrotron Radiation Lightsource

  79 shared

• Philip Walmsley

  Stanford University

  77 shared

Education

• Ph.D., Physics

  Stanford University

  1990

• B.S., Physics

  University of California, Berkeley

  1985