TY - JOUR

T1 - Spin noise of magnetically anisotropic centers

AU - Kozlov, V. O.

AU - Kuznetsov, N. S.

AU - Greilich, Alex

AU - Ryzhov, I. I.

AU - Kozlov, G. G.

AU - Zapasskii, V. S.

PY - 2023/2/28

Y1 - 2023/2/28

N2 - Spin noise spectroscopy, as a sort of magnetic resonance technique, uses, for detection of spin precession, spontaneous fluctuations of magnetization revealed as a peak in the Faraday-rotation (FR) noise spectrum at Larmor frequency. In the model of precessing magnetization, the FR noise signal should be the greatest in the Voigt geometry (with magnetic field aligned across the light propagation), and should vanish in the Faraday geometry (with the field along the probe beam). This reasoning employs, implicitly or explicitly, the so-called Van Vleck theorem that establishes, within the limits of certain assumptions, a direct relation between the FR and magnetization of the spin system. We show that violation of these assumptions in crystals with anisotropic paramagnetic centers may qualitatively change the conventional laws of spin noise detection, making, in particular, the FR noise detectable in the Faraday geometry. These conclusions are confirmed by experimental studies of spin-noise spectra of CaF2 crystals with tetragonal centers of Nd3+ ions.

AB - Spin noise spectroscopy, as a sort of magnetic resonance technique, uses, for detection of spin precession, spontaneous fluctuations of magnetization revealed as a peak in the Faraday-rotation (FR) noise spectrum at Larmor frequency. In the model of precessing magnetization, the FR noise signal should be the greatest in the Voigt geometry (with magnetic field aligned across the light propagation), and should vanish in the Faraday geometry (with the field along the probe beam). This reasoning employs, implicitly or explicitly, the so-called Van Vleck theorem that establishes, within the limits of certain assumptions, a direct relation between the FR and magnetization of the spin system. We show that violation of these assumptions in crystals with anisotropic paramagnetic centers may qualitatively change the conventional laws of spin noise detection, making, in particular, the FR noise detectable in the Faraday geometry. These conclusions are confirmed by experimental studies of spin-noise spectra of CaF2 crystals with tetragonal centers of Nd3+ ions.

UR - https://www.mendeley.com/catalogue/d53887f5-2f7e-3016-99fb-eb14aa05ce72/

U2 - 10.1103/physrevb.107.064427

DO - 10.1103/physrevb.107.064427

M3 - Article

VL - 107

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 1098-0121

IS - 6

M1 - 064427

ER -