Yusuke Iguchi, Ph.D.

Pronunciation [yoo-sooh-keh ee-gooh-chee]

Contact

Senior Research Scientist-Physical
Geballe Laboratory for Advanced Materials, Stanford University
476 Lomita Mall, McCullough Room 137, Stanford, CA 94305, USA 
email: yiguchi(at)stanford.edu

Education

PhD & MS, Department of Basic Science, The University of Tokyo, Tokyo (2018) (Advisor: Yoshinori Onose)
Teaching certificate for Science in middle & high schools, Tokyo University of Science (2013)
BS, Department of Physics, Tokyo University of Science, Tokyo (2013) (Advisor: Setsuo Mitsuda)

Employment history/work experience

2020 - current      Senior Research Scientist-Physical, Geballe Laboratory for Advanced Materials,
                               Stanford University
2018 - 2020          Postdoctoral Research Fellow, Department of Applied Physics, Stanford University
                               (Advisor: Kathryn Ann Moler)
2018 - 2020          Japan Society for the Promotion of Science Overseas Research Fellow
2016 - 2018          Research Fellow (DC2) of Japan Society for the Promotion of Science 

Honors and Awards

Selected Papers (All papers are here, all talks are here)

1. Superconducting vortices carrying a temperature-dependent fraction of the flux quantum
   Y. Iguchi, R.A. Shi, K. Kihou, C.-H. Lee, M. Barkman, A. L. Benfenati,  V. Grinenko, E. Babaev, and K. A. Moler
   Science 380, 1244-1247 (2023).

2. Microscopic imaging homogeneous and single phase superfluid density in UTe$_2$
   Y. Iguchi, H. Man, S. M. Thomas, F. Ronning, P.F.S. Rosa, and K. A. Moler
   Physical Review Letters 130, 196003 (2023)

3. Local observation of linear-T superfluid density and anomalous vortex dynamics in URu$_2$Si$_2$
   Y. Iguchi, I. P. Zhang, E. D. Bauer, F. Ronning, J. R. Kirtley, K. A. Moler
   Physical Review B (Letter) 103, L220503 (2021)

4. Microwave non-reciprocity of magnon excitations in a non-centrosymmetric antiferromagnet Ba$_2$MnGe$_2$O$_7$
   Y. Iguchi, Y. Nii, M. Kawano, H. Murakawa, N. Hanasaki, and Y. Onose
   Physical Review B 98, 064416 (2018)

5. Magnetoelectrical control of nonreciprocal microwave response in a multiferroic helimagnet
   Y. Iguchi, Y. Nii, and Y. Onose
   Nature Communications 8, 15252 (2017)

6. Nonreciprocal magnon propagation in a noncentrosymmetric ferromagnet LiFe$_5$O$_8$
   Y. Iguchi, S. Uemura, K. Ueno, and Y. Onose
   Physical Review B 92, 184419 (2015) 

Teaching Experience

2022/7-current      Girls Who Code in Japanese, Teacher, Japan
2022/5                    nano@stanford, Guest Teacher at Greenleaf TK-8 School, CA
2021/12                     Skype a Scientist, Guest Teacher at Chardon Primary School, NE
2013-2014                 Material Science Exp. II/III, University of Tokyo, Japan, Teaching Assistant
Summer 2012           Physics I, Guest Teacher at Kumagaya High School, Japan

Professional and Leadership Activities

2022/6-current     Co-Founder & Organizer, Japanese Academic Seminars at Stanford, Stanford, CA
2024/3                   Session chair, American Physical Society March Meeting 2024(Minneapolis), D16 
2023/12                 Speaker, "Unleashing Children's Potential: How to Raise Kids Who Love Math!",
                               ECC public webinar
2023/11                  Panelist, "The Interaction Crisis: Reshaping Synchronous Online Education,"
                               SpatialChat public webinar 
2023/9                  Panelist, "Network Enhancement for Overseas Japanese Research Community,"
                               1st UJA General Meeting, Consulate-General of Japan in Boston
2023/9                   Organizer, "The overseas career for Women researchers," 1st JASS&SA Webinar
2023/9                   Session chair, 78th Ann. Meeting, The Physical Society of Japan, Sendai, Japan
2022/8                   Session chair, 29th Inter. Conf. on Low Temperature Physic (LT29), Sapporo
2020/5-2021/7        Organizer, TED circle at Bechtel International Center, Stanford University, CA
2019/12                   Session chair, 32nd International Symposium on Superconductivity, Kyoto
Reviewers, Science, npj Quantum Materials, Scientific Reports, Science Progress

Visiting(short-term)

2019/1,   Max Planck Institute for Chemical Physics of Solids, Dresden, Germany (C. Hicks group)
2018/6,  Osaka University, Osaka, Japan (N. Hanasaki group)
2012/11,12, 2013/2,  Photon Factory at KEK, Tsukuba, Japan (BL-3A, H. Nakao group)
2012/10,  SPring-8, Hyogo, Japan (BL-29XU, Y. Tanaka group)
2012/4,   National Institute for Materials Science, Tsukuba, Japan  (N. Terada group)

Experimental skills

Measurements
Synchrotron X-Ray diffraction
Microwave spectroscopy(Low temperature Microwave broadband measurement in magnetic field/Design of microwave circuit/Micro Fabrication of Microwave circuit by using Photo- and EB-lithography)
Scanning SQUID microscopy
Ultra-low temperature measurement (Cryogenic dilution cryostat, Liquid He3/He4 cryostat)
Uniaxial strain measurement (Mechanical uniaxial stress/Micro uniaxial stress by piezo)

Sample growth
Polycrystal growth (EB, Spattering, Resistance heating)
Single crystal growth (Floating zone, Flux)

Others
Programing (Perl, Python, MATLAB)
Equipment Remote Control (Lab view, MATLAB, Python)
Radioactive material treatment (URu$_2$Si$_2$,UTe$_2$)

Area of Specialty

3. Local superconducting states in unconventional superconductors by using scanning SQUID Microscopy
Senior Research Scientist/Postdoc, Stanford University (2018-current):
I am working as a Senior Research Scientist at Stanford University in the Moler group after I finished my postdoctoral research in 2018-2020. We newly launched the cryogenic dilution unit (BLUEFORS) and introduced the scanning SQUID microscope to apply chiral superconductor candidates. We observed local linear-T superfluid density and coexisting ferromagnetic domains with the superconductivity in URu$_2$Si$_2$. [Phys. Rev. B(Letter) 2021] We also microscopically measured the temperature dependence of the superfluid density without any kink below $T_c$ on a newly discovered odd parity superconductor UTe$_2$, suggesting the absence of multiple superconducting phase transitions at ambient pressure and anisotropic gap structures. [Phys. Rev. Lett. 2023] We also reported the absence of any kink in the superfluid density below $T_c$ of Sr$_2$RuO$_4$ under uniaxial strains. [Phys. Rev. B 2023]

  We have also studied the statistics and dynamics of superconducting vortices at the dilution fridge and another cryogenic 4K cryostat (BLUEFORS). We observed the anisotropic vortex dynamics in the nematic superconductor FeSe. [Phys. Rev. B 2019] The observed vortex dynamics can be explained by our simulation using the toy model of the quadratic pinning potential. We also observed the isotropic and anisotropic vortex dynamics at different locations of URu$_2$Si$_2$. [Phys. Rev. B(Letter) 2021] We also observed pinned vortices and anti-vortices near zero fields in UTe$_2$, suggesting the existence of hidden internal magnetic fields. [Phys. Rev. Lett. 2023] We also observed the un-quantized vortex in a multiband superconductor K$_{0.77}$Ba$_{0.23}$Fe$_2$As$_2$. [Science 2023]

2. Non-reciprocity of magnon excitations in non-centrosymmetric magnets
MS & PhD, University of Tokyo (2013-2018):
I am a first member of Onose Laboratory. We launched the 20 GHz microwave measurement system and implemented the creation of single crystals, the design of the microwave antenna, and the micro-fabrication. We first observed the nonreciprocal microwave response via the asymmetric magnon-band in the chiral system, which is denoted as the Rashba effect in the magnon system.[Phys. Rev. B 2015] In addition, in the microwave measurement system, we observed the nonreciprocal propagation of the surface acoustic wave (SAW) via the phonon-magnon coupling[Phys. Rev. B(Rapid Communications) 2017], and we electrically and magnetically controlled the nonreciprocal propagation of microwaves in multiferroics.[Nat. Commun. 2017; J. Phys. Soc. Jpn.2017; Appl. Phys. Lett. 2022] In addition, we also designed the 40 GHz microwave measurement system. We succeeded in observing the nonreciprocal microwave propagation in antiferromagnetic multiferroics and quantitatively evaluating the nonreciprocity.[Phys. Rev. B 2018]

1. Uniaxial-Pressure Effects on Spin-Driven Lattice Distortions in Geometrically Frustrated Magnets
BS, Tokyo University of Science (2012):
We revealed that the lattice largely responds to a pressure near the phase transition point in CuFeO$_2$, which has a strong spin-lattice correlation, by the measurement of Synchrotron radiation in uniaxial press.[J. Phys. Soc. Jpn. 2013]

Doctoral Dissertation

"Non-reciprocity of magnon excitations in non-centrosymmetric magnets" (doi/10.15083/00077865)