Yusuke Iguchi

All Publications

• Anomalous Superfluid Density in a Disordered Charge-Density-Wave Material: Pd-Intercalated ErTe_{3}. Physical review letters Iguchi, Y., Straquadine, J. A., Murthy, C., Kivelson, S. A., Singh, A. G., Fisher, I. R., Moler, K. A. 2024; 133 (3): 036001

  Abstract

  We image local superfluid density in single crystals of Pd-intercalated ErTe_{3} below the superconducting critical temperature T_{c}, well below the onset temperature T_{CDW} of (disordered) charge-density-wave order. We find no detectable inhomogeneities on micron scales. We observe a rapid increase of the superfluid density below T_{c}, deviating from the behavior expected in a conventional Bardeen-Cooper-Schrieffer superconductor, and show that the temperature dependence is qualitatively consistent with a combination of quantum and thermal phase fluctuations.

  View details for DOI 10.1103/PhysRevLett.133.036001

  View details for PubMedID 39094125

• In Situ Local Imaging of Ferromagnetism and Superconductivity in RbEuFe4As4. Nano letters Man, H., Iguchi, Y., Bao, J., Chung, D. Y., Kanatzidis, M. G. 2024

  Abstract

  The coexistence of superconductivity and ferromagnetism is an intrinsically interesting research focus in condensed matter physics, but the study is limited by low superconducting (Tc) and magnetic (Tm) transition temperatures in related materials. Here, we used a scanning superconducting quantum interference device to image the in situ diamagnetic and ferromagnetic responses of RbEuFe4As4 with high Tc and Tm. We observed significant suppression of the superfluid density in the vicinity of the magnetic phase transition, signifying fluctuation-enhanced magnetic scatterings between Eu spins and Fe 3d conduction electrons. Intriguingly, we observed multiple ferromagnetic domains that should be absent in an ideal magnetic helical phase. The formation of these domains demonstrates a weak c-axis ferromagnetic component probably arising from the Eu spin-canting effect, indicative of possible superconductivity-driven domain Meissner and domain vortex-antivortex phases, as revealed in EuFe2(As0.79P0.21)2. Our observations highlight that RbEuFe4As4 is a unique system that includes multiple interplay channels between superconductivity and ferromagnetism.

  View details for DOI 10.1021/acs.nanolett.4c02475

  View details for PubMedID 39007862

• Scanning SQUID study of ferromagnetism and superconductivity in infinite-layer nickelates PHYSICAL REVIEW MATERIALS Shi, R. A., Wang, B., Iguchi, Y., Osada, M., Lee, K., Goodge, B. H., Kourkoutis, L. F., Hwang, H. Y., Moler, K. A. 2024; 8 (2)

  View details for DOI 10.1103/PhysRevMaterials.8.024802

  View details for Web of Science ID 001171649400003

• Constraints on a split superconducting transition under uniaxial strain in Sr₂RuO₄ from scanning SQUID microscopy PHYSICAL REVIEW B Mueller, E., Iguchi, Y., Watson, C., Hicks, C. W., Maeno, Y., Moler, K. A. 2023; 108 (14)

  View details for DOI 10.1103/PhysRevB.108.144501

  View details for Web of Science ID 001180023900001

• 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

  Abstract

  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

  Abstract

  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)

  View details for DOI 10.1103/PhysRevB.103.L220503

  View details for Web of Science ID 000661498500003

• 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)

  View details for DOI 10.1103/PhysRevB.100.024514

  View details for Web of Science ID 000476686700006

• 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)

  View details for DOI 10.1103/PhysRevB.98.064416

  View details for Web of Science ID 000442194600004

• Magnetoelectrical control of nonreciprocal microwave response in a multiferroic helimagnet NATURE COMMUNICATIONS Iguchi, Y., Nii, Y., Onose, Y. 2017; 8: 15252

  Abstract

  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)

  View details for DOI 10.7566/JPSJ.86.024707

  View details for Web of Science ID 000391861500022

• Nonreciprocal propagation of surface acoustic wave in Ni/LiNbO3 PHYSICAL REVIEW B Sasaki, R., Nii, Y., Iguchi, Y., Onose, Y. 2017; 95 (2)

  View details for DOI 10.1103/PhysRevB.95.020407

  View details for Web of Science ID 000391851800001

• 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

  View details for DOI 10.1021/acsphotonics.6b00272

  View details for Web of Science ID 000380297200005

• Nonreciprocal magnon propagation in a noncentrosymmetric ferromagnet LiFe5O8 PHYSICAL REVIEW B Iguchi, Y., Uemura, S., Ueno, K., Onose, Y. 2015; 92 (18)

  View details for DOI 10.1103/PhysRevB.92.184419

  View details for Web of Science ID 000364812000003

• 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)

  View details for DOI 10.7566/JPSJ.82.114711

  View details for Web of Science ID 000325793500031