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Colloquium

Upcoming Colloquium

Dr. Igor Barsukov

Magnon Condensation in Magnetic Heterostructures
Dr. Igor Barsukov, UC Riverside

October 14, 2019
11:15am in PH1-223
Refreshments in HSCI-224 from 10:45-11:05am

Spintronics seeks to provide the basis for next-generation information technologies. Energy-efficient manipulation of spin dynamics in magnetic systems plays a central role in spintronics research. I will present a magnetic nano-oscillator operating at GHz frequencies based on the principle of heat recycling.

Injection of a pure spin current into magnetic insulator modifies the chemical potential of magnons and can lead to intriguing phenomena such as long-range spin transport and magnon condensation. We study nanowires fabricated from a bilayer of a metallic ferromagnet and an insulating ferrimagnet. Via interlayer exchange coupling, magnons can be thermally transferred from one layer into another, constituting a pure spin current. The injected incoherent magnons transfer their angular momentum to a low-energy magnon state, thereby reducing its effective damping. Above the critical thermal spin current, the magnon system undergoes a phase transition establishing a coherent low-energy state. This process corresponds to bosonic condensation of non-equilibrium magnons into a magnon condensate and manifests through microwave emission from the nanowire.

This work advances our understanding of spin thermodynamics in heterogeneous systems and presents promising concepts for energy-efficient spintronic applications.

Parts of this work were supported by Spins and Heat in Nanoscale Electronic Systems (SHINES), an Energy Frontier Research Center funded by the US Department of Energy and by NSF under grant ECCS-1810541.

Figure above: Schematic of the two-magnet based nano-oscillator.

The Colloquium is a unique opportunity for students to learn about new developments in physics and what physicists do after they graduate. Hosted by the Department of Physics and Astronomy at California State University Long Beach, the weekly meetings invite guests from universities, research laboratories, and industry to present and discuss current topics in physics. All students are encouraged to attend for a well-rounded experience and training in physics.

Schedule

The Fall 2019 colloquia will start on September 9 and end on December 9.

Date Title Speaker and Affiliation
October 21, 2019 TBA Dr. Veronica Dexheimer, Kent State
October 28, 2019 TBA Dr. John Baez, UC Riverside
November 4, 2019 TBA Dr. Igor Beloborodov, CSU Northridge
November 13, 2019* TBA Dr. Vladimir Z. Kresin, Lawrence Berkeley National Laboratory

*This Colloquium, 11/13, is on a Wednesday because of Veteran's Day.

Previous Colloquia

The following are Colloquia from this semester. The Colloquium Archive has the Colloquia from previous semesters.

Date Title Speaker and Affiliation
October 14, 2019 Magnon Condensation in Magnetic Heterostructures Dr. Igor Barsukov, UC Riverside
October 7, 2019 Controlling magnetism in a Mott insulator by optical pumping Dr. David Hsieh, CalTech
September 30, 2019 Nanoengineered Materials and Interfaces for Quantum Technologies Dr. Pankaj Jha, CalTech
September 23, 2019 The Explosive Astrophysics of Gravitational Waves Dr. Jonah Kanner, CalTech
September 16, 2019 Opportunities for CSU Students to Work at CERN with NSF IRES Grant Dr. Yongsheng Gao, CSU Fresno
September 9, 2019 Meet and Mix Faculty and Staff, CSU Long Beach

Sponsors

We acknowledge with gratitude donations and support from the following present sponsors:

  • H.E. and H.B. Miller and Family Endowment
  • Benjamin Carter
  • American Physical Society
  • Anonymous

We also acknowledge with gratitude our past donors: The Forty-Niner Shops, Inc., The Northrop Grumman Foundation, Sandra Dana, Anonymous.

If you wish to support the Colloquium, please contact the colloquium coordinator or the department chair. Thank you!