Calculation of spin triplet excitons in magnetic systems

Various technical topics such as parallelism and efficiency, netCDF problems, the Yambo code structure itself, are posted here.
lz dong
Posts: 6
Joined: Mon Jun 12, 2023 7:26 am

Calculation of spin triplet excitons in magnetic systems

Dear all,
For a magnetic system, if its topmost valence band and the bottommost conduction band possess opposite spins , the exciton involved in these two bands must be spin-triplet. See https://journals.aps.org/prl/abstract/1 ... 124.166401 (Phys. Rev. Lett. 124, 166401). In this case, how do we accurate calculate the triplet exciton ? Do we need to take into account the SOC? Or set BSENGexx = 0 eV for spin polarization?

Thank You !
lz Dong
PhD student
Beijing Institute of Technology,China

Davide Sangalli
Posts: 617
Joined: Tue May 29, 2012 4:49 pm
Location: Via Salaria Km 29.3, CP 10, 00016, Monterotondo Stazione, Italy
Contact:

Re: Calculation of spin triplet excitons in magnetic systems

Dear lz Dong,
if you compute spin-flip transitions ("Delta Sz = 1"), you will get the spin flip channel of BSE.

Setting the exchange cutoff to zero in input you will get instead triplet transitions in the spin-conserving channel "Delta Sz=0"

"Delta Sz = 1" transitions are degenerate to "Delta Sz = 0" transitions for non magnetic systems.
However, they are significantly different for magnetic systems.
Indeed "Delta Sz = 1" transitions describe magnons. See for example here:
https://doi.org/10.1103/PhysRevB.103.155152

You can compute spin-flip transition by setting

Code: Select all

``BSE_prop="magn"``
Please be aware that this is an experimental feature of the code, and that the convergence of magnons in the spin-flip channel is quite different from the convergence of excitons.
I advise to use the last yambo version 5.2

Best,
D.
Davide Sangalli, PhD
CNR-ISM, Division of Ultrafast Processes in Materials (FLASHit) and MaX Centre