John B. Ketterson

About

Professor John B. Ketterson is associated with the Department of Physics at Northwestern University. His research group focuses on various aspects of condensed matter physics, including the study of patterned nano-magnet structures. His work involves broadband ferromagnetic resonance measurements, with particular interest in the vortex core resonance that occurs in patterned dots or antidot structures. These materials are of interest due to their potential applications as high-density memory storage in computing. The group also explores atom trapping techniques, as evidenced by the work of doctoral students developing magneto-optical atom traps to create Bose-Einstein condensates of rubidium. Overall, Professor Ketterson's research encompasses experimental investigations into magnetic phenomena at the nanoscale and quantum gas systems, contributing to advancements in magnetic storage technology and atomic physics.

Research topics

• Physics
• Condensed matter physics
• Quantum mechanics
• Optics
• Computer Science
• Materials science
• Geometry
• Chemistry
• Mathematics
• Atomic physics

Selected publications

• Influence of the Vertex Region on Spin Dynamics in Artificial Kagome Spin Ice

  Physical Review Applied · 2020 · 32 citations

  Stuck in the middle with you: The spin-wave mode localized in the contact area among macrospins in an artificial spin ice (ASI) is interesting for magnonic devices and applications. Detection and characterization of this mode is difficult, though. This study uses carefully designed lattices of individual macrospins with the right aspect ratio of individual nanoelements, the right geometry of macrospins on an ASI vertex, and the right configuration for clear detection of the spin dynamics. The lo…

  DOI

• Direct Observation of Bandgap Oscillations Induced by Optical Phonons in Hybrid Lead Iodide Perovskites

  Advanced Functional Materials · 2020 · 31 citations

  Abstract Hybrid organic–inorganic perovskites such as methylammonium lead iodide have emerged as promising semiconductors for energy‐relevant applications. The interactions between charge carriers and lattice vibrations, giving rise to polarons, have been invoked to explain some of their extraordinary optoelectronic properties. Here, time‐resolved optical spectroscopy is performed, with off‐resonant pumping and electronic probing, to examine several representative lead iodide perovskites. The te…

  DOI

• Control of spin dynamics in artificial honeycomb spin-ice-based nanodisks

  Physical review. B./Physical review. B · 2020 · 18 citations

  We report the experimental and theoretical characterization of the angular-dependent spin dynamics in arrays of ferromagnetic nanodisks arranged on a honeycomb lattice. The magnetic field and microwave frequency dependence, measured by broadband ferromagnetic resonance, reveal a rich spectrum of modes that is strongly affected by the microstate of the network. Based on symmetry arguments with respect to the external field, we show that certain parts of the ferromagnetic network contribute to the…

  DOI

• Amorphous to Crystal Phase Change Memory Effect with Two-Fold Bandgap Difference in Semiconducting K₂Bi₈Se₁₃

  Journal of the American Chemical Society · 2021-04-15 · 15 citations

  article

  Chalcogenide-based phase change memory (PCM) is a key enabling technology for optical data storage and electrical nonvolatile memory. Here, we report a new phase change chalcogenide consisting of a 3D network of ionic (K···Se) and covalent bonds (Bi–Se), K2Bi8Se13 (KBS). Thin films of amorphous KBS deposited by DC sputtering are structurally and chemically homogeneous and exhibit a surface roughness of 5 nm. The KBS film crystallizes upon heating at ∼483 K. The optical bandgap of the amorphous f…

  PublisherDOI

• Ferromagnetic Resonance Modes in the Exchange-Dominated Limit in Cylinders of Finite Length

  Physical Review Applied · 2021 · 10 citations

  Senior authorCorresponding

  We analyze the magnetic mode structure of axially magnetized finite-length nanoscopic cylinders in a regime where the exchange interaction dominates, along with simulations of the mode frequencies of the ferrimagnet yttrium iron garnet. For the bulk modes, we find that the frequencies can be represented by an expression given by Herring and Kittel by using wavevector components obtained by fitting the mode patterns emerging from these simulations. In addition to the axial, radial, and azimuthal…

  PublisherOA PDFDOI

Recent grants

• Manipulation of Hole-pinned Vortices: Classical and Quantum

  NSF · $510k · 2019–2023

• Collaborative Research: Collective Mode Spectroscopy in Unconventional Superconductors

  NSF · $261k · 2005–2009

• Collaborative Research: Controlled Disorder and Topological Defects in Magnetically Frustrated Thin Film Metamaterials

  NSF · $128k · 2015–2018

Frequent coauthors

• Bharat Bhushan

  280 shared

• Weiqiang Mu

  Northwestern University

  154 shared

• Swastik Kar

  Northeastern University

  148 shared

• Carlos Drummond

  Université de Bordeaux

  147 shared

• K. F. Böhringer

  University of Washington

  147 shared

• Rodolfo Miranda

  Madrid Institute for Advanced Studies

  147 shared

• Amadeo L. Vázquez de Parga

  Madrid Institute for Advanced Studies

  147 shared

• Robert Puers

  KU Leuven

  146 shared

Labs

• Ketterson Research GroupPI

  Not provided

Education

• Ph.D.

  University of Chicago

  1962

• Other

  University of Chicago

  1957

Similar researchers at Northwestern University

• Mercouri G. Kanatzidish-205
• Lin X. Chenh-92
• Chris Jacobsenh-91