Miguel Ángel Sánchez Martínez

Research

My research focuses on various aspects of theoretical condensed matter physics, with a particular emphasis on topological systems and unconventional superconductors. A central part of my work is connecting theory and experiment, with a focus on observables accessible in transport, linear optics, and nonlinear optical experiments. I also have a strong interest in the physics of topological matter in quasicrystals, with a focus on Majorana modes for quantum computing.

Current research directions

Topological matter in quasicrystals: Majorana modes for quantum computing

Emergence of Majorana modes in quasiperiodic systems, such as 1D Kitaev chains with quasicrystalline symmetries. Fractal spectra and topological phase transitions in aperiodic lattices. Higher-order topological quasiparticles in quasicrystalline systems.

Unconventional superconductivity

Optical probes of pairing in superconductors, chiral/nematic order, other optical signatures of unconventional superconductivity charactersing the topological phases₂RuO₄.

Topological quasiparticles in chiral/multifold semimetals

Linear and nonlinear optical response (e.g. SHG), circular photogalvanic effect, and transport/optical fingerprints of multifold fermions (CoSi, RhSi).

News & Blog

Notes on research and non‑research topics.

Publications

This is a short selection of representative papers. For a complete list, please refer to my profiles on Google Scholar or arXiv.

Topological quasicrystalline matter

• Fractal Topology of Majorana Bound States in Superconducting Quasicrystals
  W. Caiger, F. Flicker, M. Á. Sánchez‑Martínez†.
  arXiv preprint (2026). Majorana fermions superconductivity quasicrystals
  https://doi.org/10.48550/arXiv.2602.02796
• Giant optical response of multi‑Weyl fermions stabilized by quasicrystalline symmetries
  M. Á. Sánchez‑Martínez, I.C. Fulga, D. Varjas, A.G. Grushin, F. Flicker.
  In preparation (2026). quasicrystals optics

Superconductivity and collective modes

• Optical probes of unconventional pairing states in transition metal dichalcogenides
  M. Á. Sánchez‑Martínez†, D. Muñoz‑Segovia, F. de Juan.
  Physical Review B (2026). superconductivity optics
  https://journals.aps.org/prb/accepted/10.1103/s1wd-25dz
• Momentum relaxation cutoff of Pines’ demon in Sr₂RuO₄
  M. Á. Sánchez‑Martínez, L.C. Rhodes, P. Wahl, B. Goutéraux, L. Rademaker, F. Flicker.
  In preparation (2026). collective modes Sr₂RuO₄

Topological multifold fermions and nonlinear optics

• Second‑harmonic generation in the topological multifold semimetal RhSi
  B. Lu, S. Sayyad, M. Á. Sánchez‑Martínez, K. Manna, C. Felser, A.G. Grushin, D. Torchinsky.
  Phys. Rev. Research 4, L022022 (2022). SHG multifold fermions
  https://doi.org/10.1103/PhysRevResearch.4.L022022
• Optical signatures of multifold fermions in the chiral topological semimetal CoSi
  B. Xu*, Z. Fang*, M. Á. Sánchez‑Martínez*, J.W.F. Venderbos, Z. Ni, T. Qiu, K. Manna, W. Wang, J. Paglione, C. Bernhard, C. Felser, E.J. Mele, A.G. Grushin, A.M. Rappe, L. Wu.
  PNAS 2020, 2010752117 (2020). multifold fermions optics
  https://doi.org/10.1073/pnas.2010752117
• Linear and nonlinear optical responses in the chiral multifold semimetal RhSi
  Z. Ni, B. Xu, M. Á. Sánchez‑Martínez, Y. Zhang, K. Manna, C. Bernhard, J.W.F. Venderbos, F. de Juan, C. Felser, A.G. Grushin, L. Wu.
  npj Quantum Materials 5, 96 (2020). nonlinear optics multifold fermions
  https://doi.org/10.1038/s41535-020-00187-y
• Linear optical conductivity of chiral multifold fermions
  M.‑Á. Sánchez‑Martínez, F. de Juan, A.G. Grushin.
  Phys. Rev. B 99, 155145 (2019). theory multifold fermions
  https://doi.org/10.1103/PhysRevB.99.155145

Other publications

• Spinon mediation of witness‑spin dynamics and ground state in herbertsmithite
  H. Takahashi, J. Murphy, M. Wood‑Thanan, P. Puphal, M. Á. Sánchez‑Martínez, F. Jerzembeck, C.C. Hsu, J. Ward, M. Isobe, Y. Matsumoto, H. Takagi, S. Blundell, M. Norman, F. Flicker, J.C. Séamus Davis.
  Under consideration in Nature Physics (2025). spin liquids herbertsmithite
  https://arxiv.org/abs/2510.11678
• Linear and nonlinear optical responses of chiral multifold semimetals
  M. Á. Sánchez‑Martínez.
  Springer Theses Series, Springer‑Nature, Cham (2023). book
  https://link.springer.com/book/10.1007/978-3-031-25771-1
• Spectral and optical properties of Ag₃Au(Se₂,Te₂) and dark matter detection
  M.‑Á. Sánchez‑Martínez*, I. Robredo*, A. Bidaurrazaga, A. Bergara, F. de Juan, A.G. Grushin, M.G. Vergniory.
  J. Phys. Mater. 3, 014001 (2019). spectral optics
  https://doi.org/10.1088/2515-7639/ab3ea2
• Impact of the regularization parameter in the mean free path reconstruction method: Nanoscale heat transport and beyond
  M.-Á. Sánchez‑Martínez, F. Alzina, J. Oyarzo, C.M. Sotomayor Torres, E. Chavez‑Angel.
  Nanomaterials 9, 414 (2019). nanoscale heat phonons
  https://doi.org/10.3390/nano9030414

Recent talks and seminars

Selected recent invitations and conference contributions.

• Abundance of Majorana modes in quasicrystals (poster by W. Caiger, co‑supervised)
  SDIQT25 International Workshop. Salamanca, Spain · Jun 2025.
• Unraveling Pines’ demon in Sr₂RuO₄ (invited)
  University of Geneva (invited by Prof. Louk Rademaker). Geneva, Switzerland · Jun 2024.
• Linear optical response of chiral multifold fermions
  NGSCES 2024 International Conference. Girona, Spain · Oct 2024.
• Unraveling Pines’ demon in Sr₂RuO₄ (poster)
  Electrons, Photons and Plasmons 2024 Workshop. Nyon, Switzerland · Jun 2024.
• Unraveling Pines’ demon in Sr₂RuO₄ (oral)
  Condensed Matter Physics in the City 2024 · Jun 2024.
• Fingerprints of multifold fermions in optics: linear and nonlinear optical responses of CoSi and RhSi (oral)
  APS March Meeting 2023, Session M25. Las Vegas, USA · Mar 2023.
• Unconventional fermions and where to find them: linear and nonlinear optical responses of CoSi and RhSi (poster)
  GEFES 2023 (RSEF). Salamanca, Spain · 2023.
• Unconventional fermions and how to find them: optical probes of chiral multifold semimetals (oral)
  International Focus Workshop in Topological Materials: From Weak to Strong Correlations. MPIPKS, Dresden, Germany · Apr 2022.
• Linear and nonlinear optical responses of chiral multifold semimetals (oral)
  APS March Meeting 2022, Session Y59. Chicago, USA · Mar 2022. (MCAA Micro Travel Grant, SCHINEs)
• Optical signatures of multifold fermions in chiral topological semimetals RhSi and CoSi (poster)
  LEES 2021: Low‑Energy Electrodynamics in Solids. Virtual · Jun–Jul 2021.
• Linear and nonlinear optical responses of chiral multifold semimetals (invited)
  Nanyang Technological University (invited by Prof. Justin Song). Virtual · Sep 2021.
• Optical signatures of multifold fermions in RhSi and CoSi (oral)
  APS March Meeting 2021, Session A45. Virtual · Mar 2021.
• Linear optical conductivity of the chiral multifold semimetal RhSi (poster)
  Dynamics of Emerging Quasiparticles in Topological Dirac Materials (WE‑Heraeus 731). Bad Honnef, Germany · Oct 2020.
• Optical conductivity of the multifold semimetal RhSi (poster)
  CMD 2020 GEFES (RSEF‑GEFES & EPS‑CMD). Virtual · Aug–Sep 2020.
• Charge dynamics of metallic and superconducting islands coupled to metallic leads (oral)
  Microsoft Station Q Research Intern Talk. Santa Barbara, USA · Jun 2020.
• Blackboard Seminar: Multifold fermions in conventional crystals
  Kavli Institute for Theoretical Physics (Spin & Heat Transport in Quantum and Topological Materials program). Santa Barbara, USA · Oct–Dec 2019.
• Linear optical response of chiral multifold fermions (poster)
  Ultrafast and Nonlinear Dynamics of Quantum Materials. Univ. Paris‑Diderot, France · Jun 2019.
• Linear optical response of chiral multifold fermions (oral)
  NGSCES 2018 International Conference. Donostia‑San Sebastián, Spain · Sep 2018.
• A paradigm for anomalies and non‑linear responses in topological matter (poster)
  LETI Innovation Days, 2nd Quantum Engineering Day. Grenoble, France · Jul 2018.
• The role of the reconstruction parameter in MFP reconstruction technique (oral)
  3rd Scientific Meeting of BCN‑b PhD Students in Nanoscience. Barcelona, Spain · Nov 2017.
• Impact of the regularization parameter in the MFP reconstruction technique (oral)
  III Severo Ochoa Scientific Workshop. ICN2, Barcelona, Spain · Jun 2017.
• Dependence of the accumulation function on the regularization parameter in MFP reconstruction (poster)
  Wave Phenomena and Phonon Thermal Transport. Oléron, France · Jun 2017.
• Study of the impact of the regularization parameter in the phonon MFP reconstruction (poster)
  E‑MRS Spring Meeting. Strasbourg, France · May 2017.
• Perturbative quantization of Yang‑Mills theory with the classical double of su(N) (oral)
  III Doctoral Conference of the University of Murcia. Murcia, Spain · May–Jun 2017.

Students

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