Dr. Iguchi received his B.S. in physics at Tokyo University of Science in 2013 and received his Ph.D. in Basic Science from the University of Tokyo in 2018. He was JSPS Overseas Fellow in Applied Physics at Stanford University during 2018-2020. He then joined the Geballe Laboratory for Advanced Materials at Stanford University as a senior research scientist. Since 2018, he has worked in Prof. Kathryn Ann Moler’s group.

Dr. Iguchi is an experimental physicist in the field of condensed matter physics, with a focus on unconventional superconductors and non-centrosymmetric magnets. His wide-ranging research covers diverse areas, including the exploration of spin dynamics in ferromagnetic insulators and chiral edge currents in topological superconductors. His achievements include the observation of non-reciprocal magnon-propagation in chiral ferromagnets, pioneering electromagnetic control over non-reciprocal microwave propagation in multiferroic materials, uncovering local superconducting states and intrinsic magnetism in candidates for chiral superconductors, and the observation of unquantized vortices in multiband superconductors.

Academic Appointments

Administrative Appointments

  • Co-Founder/Organizer, Girls Who Code in Japanese (2022 - Present)
  • Co-Founder/Organizer, Japanese Academic Seminars at Stanford (JASS) (2022 - Present)

Honors & Awards

  • Overseas Research Fellowship, Japan Society for the Promotion of Science (2018/04)
  • JPSJ Papers of Editors' Choice, Journal of Physical Society of Japan (2017/01)
  • Research Fellowship DC2, Japan Society for the Promotion of Science (2016/04)
  • Outstanding Graduate Student Award, Graduate School of Arts and Sciences, The University of Tokyo (2015/03)

Professional Education

  • Postdoc, Department of Applied Physics, Stanford University (2020)
  • Ph.D., Department of Basic Science, The University of Tokyo, Tokyo (2018)
  • M.S., Department of Basic Science, The University of Tokyo, Tokyo (2015)
  • B.S., Department of Physics, Tokyo University of Science, Tokyo (2013)

Current Research and Scholarly Interests

Scanning SQUID (Superconducting QUantum Interference Device) microscopy, which can obtain the local susceptibility by measuring an absolute value of magnetic flux, is very unique and strong scanning magnetic probe. The purpose of this project is to reveal the local superconducting states of unconventional superconductors, such as chiral superconductor candidates, by using the scanning SQUID microscope. Recent projects are the following.

1. Imaging vortex dynamics in multiband superconductors
-Anisotropic vortex pinning potential along the twin boundaries of FeSe
(Phys. Rev. B 100, 024514 (2019))
-Isotropic and anisotropic pinning potentials at different locations of URu2Si2
(Phys. Rev. B (Letter) 103, L220503 (2021))
-Unquantized flux in a superconducting vortex at KxBa1-xFe2As2
(Science 380, 1244-1247 (2023))

2. Imaging superfluid density and spontaneous magnetism in chiral superconductor candidates
-Linear-T superfluid density and absence of spontaneous edge currents in URu2Si2
(Phys. Rev. B (Letter) 103, L220503 (2021))
-Single-phase superfluid density in high-quality UTe2
(Phys. Rev. Lett, 130, 196003 (2023))

All Publications

  • Superconducting vortices carrying a temperature-dependent fraction of the flux quantum. Science (New York, N.Y.) Iguchi, Y., Shi, R. A., Kihou, K., Lee, C., Barkman, M., Benfenati, A. L., Grinenko, V., Babaev, E., Moler, K. A. 2023: eabp9979


    Magnetic field penetrates type-II bulk superconductors by forming quantum vortices that enclose a magnetic flux equal to the magnetic flux quantum. The flux quantum is a universal quantity that depends only on fundamental constants. Here we investigate isolated vortices in the hole-overdoped Ba1-xKxFe2As2 (x = 0.77) by using scanning superconducting quantum interference device (SQUID) magnetometry. In many locations, we observed vortices that carried only part of a flux quantum, with a magnitude that varied continuously with temperature. We interpret these features as quantum vortices with non-universally quantized (fractional) magnetic flux whose magnitude is determined by the temperature-dependent parameters of a multiband superconductor. The demonstrated mobility and manipulability of the fractional vortices may enable applications in fluxonics-based computing.

    View details for DOI 10.1126/science.abp9979

    View details for PubMedID 37262195

  • Microscopic Imaging Homogeneous and Single Phase Superfluid Density in UTe_{2}. Physical review letters Iguchi, Y., Man, H., Thomas, S. M., Ronning, F., Rosa, P. F., Moler, K. A. 2023; 130 (19): 196003


    Odd-parity superconductor UTe_{2} shows spontaneous time-reversal symmetry breaking and multiple superconducting phases, which imply chiral superconductivity, but only in a subset of samples. Here we microscopically observe a homogeneous superfluid density n_{s} on the surface of UTe_{2} and an enhanced superconducting transition temperature near the edges. We also detect vortex-antivortex pairs even at zero magnetic field, indicating the existence of a hidden internal field. The temperature dependence of n_{s}, determined independent of sample geometry, does not support point nodes along the b axis for a quasi-2D Fermi surface and provides no evidence for multiple phase transitions in UTe_{2}.

    View details for DOI 10.1103/PhysRevLett.130.196003

    View details for PubMedID 37243629

  • Nonreciprocal microwave response at room temperature in multiferroic Y-type hexaferrite BaSrCo2Fe11AlO22 APPLIED PHYSICS LETTERS Hirose, S., Iguchi, Y., Nii, Y., Kimura, T., Onose, Y. 2022; 121 (22)

    View details for DOI 10.1063/5.0124283

    View details for Web of Science ID 000891200900004

  • Local observation of linear-T superfluid density and anomalous vortex dynamics in URu2Si2 PHYSICAL REVIEW B Iguchi, Y., Zhang, I. P., Bauer, E. D., Ronning, F., Kirtley, J. R., Moler, K. A. 2021; 103 (22)
  • Imaging anisotropic vortex dynamics in FeSe PHYSICAL REVIEW B Zhang, I. P., Palmstrom, J. C., Noad, H., Bishop-Van Horn, L., Iguchi, Y., Cui, Z., Mueller, E., Kirtley, J. R., Fisher, I. R., Moler, K. A. 2019; 100 (2)
  • Microwave nonreciprocity of magnon excitations in the noncentrosymmetric antiferromagnet Ba2MnGe2O7 PHYSICAL REVIEW B Iguchi, Y., Nii, Y., Kawano, M., Murakawa, H., Hanasaki, N., Onose, Y. 2018; 98 (6)
  • Magnetoelectrical control of nonreciprocal microwave response in a multiferroic helimagnet NATURE COMMUNICATIONS Iguchi, Y., Nii, Y., Onose, Y. 2017; 8: 15252


    The control of physical properties by external fields is essential in many contemporary technologies. For example, conductance can be controlled by a gate electric field in a field effect transistor, which is a main component of integrated circuits. Optical phenomena induced by an electric field such as electroluminescence and electrochromism are useful for display and other technologies. Control of microwave propagation is also important for future wireless communication technology. Microwave properties in solids are dominated mostly by magnetic excitations, which cannot be easily controlled by an electric field. One solution to this problem is to use magnetically induced ferroelectrics (multiferroics). Here we show that microwave nonreciprocity, that is, different refractive indices for microwaves propagating in opposite directions, could be reversed by an external electric field in a multiferroic helimagnet Ba2Mg2Fe12O22. This approach offers an avenue for the electrical control of microwave properties.

    View details for DOI 10.1038/ncomms15252

    View details for Web of Science ID 000400861300001

    View details for PubMedID 28480887

    View details for PubMedCentralID PMC5424162

  • Microwave Magnetochiral Effect in the Non-centrosymmetric Magnet CuB2O4 JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Nii, Y., Sasaki, R., Iguchi, Y., Onose, Y. 2017; 86 (2)
  • Nonreciprocal propagation of surface acoustic wave in Ni/LiNbO3 PHYSICAL REVIEW B Sasaki, R., Nii, Y., Iguchi, Y., Onose, Y. 2017; 95 (2)
  • Terahertz Radiation by Subpicosecond Magnetization Modulation in the Ferrimagnet LiFe5O8 ACS PHOTONICS Kinoshita, Y., Kida, N., Sotome, M., Miyamoto, T., Iguchi, Y., Onose, Y., Okamoto, H. 2016; 3 (7): 1170–75
  • Nonreciprocal magnon propagation in a noncentrosymmetric ferromagnet LiFe5O8 PHYSICAL REVIEW B Iguchi, Y., Uemura, S., Ueno, K., Onose, Y. 2015; 92 (18)
  • Uniaxial-Pressure Effects on Spin-Driven Lattice Distortions in Geometrically Frustrated Magnets CuFe1-xGaxO2 (x=0, 0.035) JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Nakajima, T., Iguchi, Y., Tamatsukuri, H., Mitsuda, S., Yamasaki, Y., Nakao, H., Terada, N. 2013; 82 (11)