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SUMMARY:Magneto-optical detection of the orbital Hall effect in a light me
 tal Ti - Young Gwan Choi\, Max Planck Institute for Chemical Physics of So
 lids\, Dresden\, Germany
DTSTART:20240502T143000Z
DTEND:20240502T160000Z
UID:TALK216436@talks.cam.ac.uk
CONTACT:Julie Smith
DESCRIPTION:The experimental observation of the orbital Hall effect (OHE) 
 in a light metal Ti using the magneto-optical Kerr effect (MOKE) will be p
 resented [1]. The OHE is the generation of electron orbital angular moment
 um flow transverse to an external electric field\, and although circumstan
 tial evidence has been growing\, direct detection has remained elusive [2]
 . Previously\, theoretical studies predicted that the OHE is a fundamental
  origin of the spin Hall effect (SHE) in many transition metals [3]. Our e
 xperimental results confirm the existence of the OHE in a light element me
 tal Ti with an unexpectedly long orbital relaxation length\, ~70 nm. We fo
 und that the MOKE signal due to the OHE-induced orbital moment is orders o
 f magnitude larger than that due to the spin moment induced by the SHE in 
 Ti. Moreover\, we examined the torque efficiency and the orbital relaxatio
 n length using orbital torque experiments with a ferromagnet layer. This o
 bservation challenges the belief that orbital angular momentum is quenched
  in solids. The presentation will also discuss the potential of using the 
 orbital degree of freedom as an information carrier and the importance of 
 studying the orbital degree of freedom. The findings significantly impact 
 the electrical control of magnetism and underscore the need for an improve
 d understanding of OHE dynamics in various materials. Moreover\, this pres
 entation will also explore further directions for OHE studies using other 
 techniques such as nitrogen-vacancy scanning and x-ray circular dichroism.
 \n\n[1] Choi\, Y.-G.\, Jo\, D.\, Ko\, K.\, Go\, D.\, Kim\, K.-H. Park\, H.
  G.\, Kim\, C.\, Min. B.-C.\, Choi\, G.-M.\, and Lee\, H.-W. Nature 619\, 
 52-56 (2023).\n[2] Bernevig\, B. A.\, Hughes\, T. L. & Zhang\, S. C. Orbit
 ronics: the intrinsic orbital current in p-doped silicon. Phys. Rev. Lett.
  95\, 066601 (2005).\n[3] Kontani\, H.\, Tanaka\, T.\, Hirashima\, D. S.\,
  Yamada\, K. & Inoue\, J. Giant Orbital Hall Effect in Transition Metals: 
 Origin of Large Spin and Anomalous Hall Effects. Phys. Rev. Lett. 102\, 01
 6601 (2009).  \n\nYoung-Gwan was born in Daejeon and raised in Seoul and A
 nsan\, South Korea. He earned his M.S. degree from the Department of Physi
 cs and Photon Science at the Gwangju Institute of Science and Technology (
 GIST)\, conducting laser spectroscopy studies on charge and heat transport
 s in condensed matters in Professor Jong-Seok Lee's laboratory. Subsequent
 ly\, he pursued his Ph.D. at the Department of Energy Science\, Sungkyunkw
 an University (SKKU)\, collaborating with Professor Gyung-Min Choi on stud
 ies involving charge\, spin\, and orbital transports optically. Currently\
 , Young-Gwan is a postdoctoral researcher at the Max Planck Institute for 
 Chemical Physics of Solids (MPI-CPfS)\, where he studies a single spin qub
 it states-based quantum sensing technique (nitrogen-vacancy scanning) with
  Dr. Uri Vool’s group and conducts research on x-ray magnetism.	
LOCATION:Goldsmiths 2 & https://zoom.us/j/96836714124
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