Upcoming Colloquium
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!