On-line SPICE-SPIN+X Seminars

On-line Seminar: 3 June 2020 - 15:00 (CET)

Probing ultrafast spin transport with terahertz electromagnetic pulses

Tobias Kampfrath, Freie Unversität Berlin and Fritz Haber Institute of the Max Planck Society, Berlin

Transport of spins is often driven by heat gradients and electric fields. To probe the initial elementary steps which lead to the formation of spin currents, we need to launch and measure transport on femtosecond time scales. This goal is achieved by employing both ultrashort optical and terahertz electromagnetic pulses. We illustrate our experimental approach by several examples including the spin Seebeck effect (see figure) and anisotropic magnetoresistance.

 

References

• [1] Seifert et al., Nature Comm. 9, Article number: 2899 (2018)
• [2] Seifert et al., J. Phys. D: Appl. Phys. 51, 364003 (2018)

PDF file of the talk available here

On-line SPICE-SPIN+X Seminars

On-line Seminar: 27.05.2020 - 15:00 (CET)

Half-integer charge transfer by Majorana edge modes

Carlo Beenakker, Leiden University

A Josephson junction in a chiral p-wave superconductor can inject a charge e/2 into a normal-metal contact, carried by chiral Majorana edge modes. We address the question whether this half-integer charge is a sharp observable, without quantum fluctuations. Because the Majorana modes are gapless, they support charge fluctuations in equilibrium at zero temperature. But we find that the excess noise introduced out of equilibrium by the e/2 charge transfer vanishes. We discuss a strategy to reduce the equilibrium fluctuations, by means of a heavy-tailed time-dependent detection efficiency, to achieve a fully noiseless half-integer charge transfer.

 

 

PDF file of the talk available here

This seminar is now  directly linked here and in the SPICE YouTube Channel. Please subscribe to receive the Zoom log-in information. 

On-line SPICE-SPIN+X Seminars

On-line Seminar: 20.05.2020 - 15:00 (CET)

Antiferromagnetic spintronics: from memories to ultra-fast optics and topological transport

Tomas Jungwirth, Institute of Physics of the Science Academy of the Czech Republic

Fifty years ago, Louis Néel pointed out in his Nobel lecture that while interesting from theoretical viewpoint, antiferromagnets did not seem to have any applications. Indeed, the alternating directions of magnetic moments on individual atoms and the resulting zero net magnetization have made antiferromagnets hard to control by the magneto-recording tools common in ferromagnets. This has hindered both the research and utility of these abundant magnetic materials. Replacing magnetic fields with modern spintronic tools has recently prompted renewed research interest in antiferromagnets. Experimental studies in antiferromagnets have successfully adapted concepts from ferromagnetic spintronics for storing, writing, and reading information. Besides electronic memory devices, antiferromagnetic spintronics has also demonstrated its utility in the research of ultra-fast optical manipulation of magnets or topological magneto-transport. In the talk we will give an overview of these diverse areas of the emerging field of antiferromagnetic spintronics.

PDF file of the talk available here

This seminar is  directly linked here and in the SPICE YouTube Channel.

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