ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

május 6. péntek 10h15,

1111 Budapest, Budafoki út 8., BME F III. magasföldszint 01.,
Elméleti Fizika Tanszék szemináriumi szoba
és
online a Microsoft Teams-ben
<https://teams.microsoft.com/l/meetup-join/19%3ae1a26210676841cdbb27bb01cf353392%40thread.tacv2/1651675714095?context=%7b%22Tid%22%3a%226a3548ab-7570-4271-91a8-58da00697029%22%2c%22Oid%22%3a%22c7eaf7d2-684b-4597-b217-6a9121400219%22%7d>

Palotás Krisztián (Wigner FK / BME Elm. Fiz.):
Magnetic skyrmions probed and manipulated by spin-polarized scanning
tuneling microscopy

The controlled creation and annihilation of individual magnetic skyrmions
have been demonstrated by using spin-polarized scanning tunneling
microscopy (SP-STM) [1], where the spin-polarized current exerts a torque
on the spin moments of the sample. This is a promising step towards future
technological applications using skyrmions for carrying or storing
information. However, the detailed microscopic mechanisms of these
processes are presently unknown. Our work contributes to this understanding
by a theoretical investigation of the tunneling electron charge and spin
transport probing magnetic skyrmions. The spin-polarized charge current (I)
and tunneling spin transport vector quantities, the longitudinal spin
current and the spin transfer torque (STT), are consistently calculated
within a simple electron transport theory [2]. The electron tunneling model
is extended to SP-STM in high spatial resolution, and applied to magnetic
skyrmions [3,4]. Besides the vector spin transport characteristics, the
relationships among conventional charge current SP-STM images [5], the
magnitudes of the spin transport quantities [3], and the topology of
various skyrmionic objects [6] are analyzed. It is also shown that at
specific SP-STM tip positions the STT efficiency  can reach very high
values close to the theoretical maximum, h/e [7]. Thus, a theoretical
prediction for a possibly highly efficient localized magnetic switching is
also provided. As an ongoing work, the extension of the tunneling spin
transport model to higher level transport theories will be briefly shown,
and the incorporation of the calculated tunneling STT into an atomistic
spin dynamics model will be outlined.


[1] N. Romming et al., Science 341, 636 (2013).
[2] K. Palotás et al., Phys Rev B 94, 064434 (2016).
[3] K. Palotás et al., Phys Rev B 97, 174402 (2018).
[4] K. Palotás, Phys Rev B 98, 094409 (2018).
[5] K. Palotás et al., Phys Rev B 96, 024410 (2017).
[6] L. Rózsa et al., Phys Rev B 95, 094423 (2017).
[7] K. Palotás et al., J Magn Magn Mater 519, 167440 (2021).


Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor