ELFT HÍRADÓ

[Andras Palyi <andraspalyi AT caesar.elte.hu>]

A BME-MTA Egzotikus Kvantumfázisok csoport következő szemináriuma:

Okvátovity Zoltán (BME)
Anomalous hyperfine coupling and nuclear magnetic relaxation in Weyl 
semimetals

2016. december 6., kedd, 14:15
BME Elméleti Fizika Tanszék szemináriumi szobája (F épület, 3. lépcsőház, 
magasföldszint)

Kivonat: 
“The electron-nuclear hyperfine interaction shows up in a variety of 
phenomena including e.g. NMR studies of correlated states and spin 
decoherence effects in quantum dots. Here we focus on the hyperfine coupling 
and the NMR spin relaxation time, T1 in Weyl semimetals. Since the density of 
states in Weyl semimetals varies with the square of the energy around the 
Weyl point, a naive power counting predicts a 1/(T1*T) ~ E^4 scaling with E 
the maximum of temperature (T) and chemical potential. By carefully 
investigating the hyperfine interaction between nuclear spins and Weyl 
fermions, we find that while its spin part behaves conventionally, its 
orbital part diverges unusually with the inverse of energy around the Weyl 
point. Consequently, the nuclear spin relaxation rate scales in a graphene 
like manner as 1/(T1*T) ~ E^2 ln(E/ω0) with ω0 the nuclear Larmor frequency. 
This allows us to identify an effective hyperfine coupling constant, which is 
tunable by gating or doping, which is relevant for decoherence effect in 
spintronics devices and double quantum dots where hyperfine coupling is the 
dominant source of spin-blockade lifting.”

Minden érdeklődőt szeretettel várunk.

A szemináriumsorozat programja: 
http://exotic.phy.bme.hu/seminars.html

Üdvözlettel,
Pályi András