Spin dynamics near the critical point

Yoshiki Kuramoto

Yoshiki Kuramoto; Spin Wave Spectrum Near the Critical Point: A Physical Aspect of the Dynamical Scaling, Progress of Theoretical Physics, Volume 41, Issue 3, 1

Xiao-Chuan Wu, Ran Cheng, Di Xiao

Shengjun Yuan, Hans A. De Raedt, Seiji Miyashita

We study the real-time domain-wall dynamics near a quantum critical point of the one-dimensional anisotropic ferromagnetic spin $1∕2$ chain. By numerical simulation, we find that the domain wall is dynamically stable in the Heisenberg-Ising model. Near the quantum critical point, the width of the domain wall diverges as ${(\ensuremath{\Delta}\ensuremath{-}1)}^{\ensuremath{-}1∕2}$.

Sergei V. Maleev

Mikhail Gennag'evich Vasin, S. V. Remizov, Andrey A. Elistratov

Ar. Abanov, Andrey V. Chubukov

We consider spin and electronic properties of itinerant electron systems, described by the spin-fermion model, near the antiferromagnetic critical point. We expand in the inverse number of hot spots in the Brillouin zone, $N$, and present the results beyond the previously studied $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{\infty}$ limit. We found two new effects: (i) Fermi surface becomes nested at hot spots, and (ii) vertex corrections give rise to anomalous spin dynamics and change the dynamical critical exponent from $z\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2$ to $z>2$. To first order in $1/N$ we found $z\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2N/(N\ensuremath{-}2)$ which for a physical $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}8$ yields $z\ensuremath{\approx}2.67$.