We report the anomalous D'yakonov-Perel' spin relaxation in ultracold spin-orbit-coupled ${}^{40}$ K gas when the coupling between $|9/2,9/2\ensuremath{\rangle}$ and $|9/2,7/2\ensuremath{\rangle}$ states, acting as an effective Zeeman magnetic field, is much stronger than the spin-orbit coupled field. Both the transverse and longitudinal spin relaxations are investigated with small and large spin polarizations. It is found that with small spin polarization, the transverse (longitudinal) spin relaxation is divided into four (two) regimes: the normal weak scattering regime, the anomalous D'yakonov-Perel'-like regime, the anomalous Elliott-Yafet-like regime, and the normal strong scattering regime (the anomalous Elliott-Yafet-like regime and the normal strong scattering regime). With large spin polarization, we find that the Hartree-Fock self-energy, which acts as an effective magnetic field, can markedly suppress the transverse spin relaxation in both weak and strong scattering limits. Moreover, by noting that as both the momentum relaxation time and the Hartree-Fock effective magnetic field vary with the scattering length in cold atoms, the anomalous D'yakonov-Perel'-like regime is suppressed and the transverse spin relaxation is hence divided into three regimes in the scattering length dependence: the normal weak scattering regime, the anomalous Elliott-Yafet-like regime, and the strong scattering regime. On the other hand, the longitudinal spin relaxation is again divided into the anomalous Elliott-Yafet-like and normal strong scattering regimes. Furthermore, it is found that the longitudinal spin relaxation can be either enhanced or suppressed by the Hartree-Fock effective magnetic field if the spin polarization is parallel or antiparallel to the effective Zeeman magnetic field.We report the anomalous D'yakonov-Perel' spin relaxation in ultracold spin-orbit-coupled ${}^{40}$K gas when the coupling between $|9/2,9/2\ensuremath{\rangle}$ and $|9/2,7/2\ensuremath{\rangle}$ states, acting as an effective Zeeman magnetic field, is much stronger than the spin-orbit coupled field. Both the transverse and longitudinal spin relaxations are investigated with small and large spin polarizations. It is found that with small spin polarization, the transverse (longitudinal) spin relaxation is divided into four (two) regimes: the normal weak scattering regime, the anomalous D'yakonov-Perel'-like regime, the anomalous Elliott-Yafet-like regime, and the normal strong scattering regime (the anomalous Elliott-Yafet-like regime and the normal strong scattering regime). With large spin polarization, we find that the Hartree-Fock self-energy, which acts as an effective magnetic field, can markedly suppress the transverse spin relaxation in both weak and strong scattering limits. Moreover, by noting that as both the momentum relaxation time and the Hartree-Fock effective magnetic field vary with the scattering length in cold atoms, the anomalous D'yakonov-Perel'-like regime is suppressed and the transverse spin relaxation is hence divided into three regimes in the scattering length dependence: the normal weak scattering regime, the anomalous Elliott-Yafet-like regime, and the strong scattering regime. On the other hand, the longitudinal spin relaxation is again divided into the anomalous Elliott-Yafet-like and normal strong scattering regimes. Furthermore, it is found that the longitudinal spin relaxation can be either enhanced or suppressed by the Hartree-Fock effective magnetic field if the spin polarization is parallel or antiparallel to the effective Zeeman magnetic field.

arXiv:1309.0727Physical Review AOct 22, 201311 citations

Searching for anomalous spin-spin interactions

Attaallah Almasi, Himawan W. Winarto, Junyi Lee +1 more

Bulletin of the American Physical SocietyJun 7, 20170 citations

Anomalous Diffusion and Griffiths Effects Near the Many-Body Localization Transition

Kartiek Agarwal, Sarang Gopalakrishnan, Michael Knap +2 more

We explore the high-temperature dynamics of the disordered, one-dimensional XXZ model near the many-body localization (MBL) transition, focusing on the delocalized (i.e., "metallic") phase. In the vicinity of the transition, we find that this phase has the following properties: (i) local magnetization fluctuations relax subdiffusively; (ii) the ac conductivity vanishes near zero frequency as a power law; and (iii) the distribution of resistivities becomes increasingly broad at low frequencies, approaching a power law in the zero-frequency limit. We argue that these effects can be understood in a unified way if the metallic phase near the MBL transition is a quantum Griffiths phase. We establish scaling relations between the associated exponents, assuming a scaling form of the spin-diffusion propagator. A phenomenological classical resistor-capacitor model captures all the essential features.We explore the high-temperature dynamics of the disordered, one-dimensional XXZ model near the many-body localization (MBL) transition, focusing on the delocalized (i.e., "metallic") phase. In the vicinity of the transition, we find that this phase has the following properties: (i) local magnetization fluctuations relax subdiffusively; (ii) the ac conductivity vanishes near zero frequency as a power law; and (iii) the distribution of resistivities becomes increasingly broad at low frequencies, approaching a power law in the zero-frequency limit. We argue that these effects can be understood in a unified way if the metallic phase near the MBL transition is a quantum Griffiths phase. We establish scaling relations between the associated exponents, assuming a scaling form of the spin-diffusion propagator. A phenomenological classical resistor-capacitor model captures all the essential features.

arXiv:1408.3413Physical Review LettersApr 23, 2015411 citations

Magnetic relaxation and He4 coverage in superfluid A13

Qiang Jiang, Haruo Kojima

Measurements on spin relaxation time in superfluid $^{3}\mathit{A}_{1}$ were carried out at a pressure of 22.4 bar and a static field of 7.5 kG. The influence of surface coverage by $^{4}\mathrm{He}$ was systematically explored. The $^{4}\mathrm{He}$ coverage is used to eliminate the spin relaxation at the boundary walls and to extract the spin relaxation time in the warmer half of bulk ${\mathit{A}}_{1}$ phase. The bulk spin relaxation time is much shorter than expected from Leggett-Takagi theory applied to the ${\mathit{A}}_{1}$ phase. In the colder half of the phase, $^{4}\mathrm{He}$ coverage anomalously has no effect on the spin relaxation time.Measurements on spin relaxation time in superfluid $^{3}\mathit{A}_{1}$ were carried out at a pressure of 22.4 bar and a static field of 7.5 kG. The influence of surface coverage by $^{4}\mathrm{He}$ was systematically explored. The $^{4}\mathrm{He}$ coverage is used to eliminate the spin relaxation at the boundary walls and to extract the spin relaxation time in the warmer half of bulk ${\mathit{A}}_{1}$ phase. The bulk spin relaxation time is much shorter than expected from Leggett-Takagi theory applied to the ${\mathit{A}}_{1}$ phase. In the colder half of the phase, $^{4}\mathrm{He}$ coverage anomalously has no effect on the spin relaxation time.

Physical review. B, Condensed matterJun 1, 19922 citations

We report the anomalous D'yakonov-Perel' spin relaxation in ultracold spin-orbit-coupled

{}^{40}

K gas when the coupling between $|9/2,9/2\ensuremath{\rangle}$ and $|9/2,7/2\ensuremath{\rangle}$ states, acting as an effective Zeeman magnetic field, is much stronger than the spin-orbit coupled field. Both the transverse and longitudinal spin relaxations are investigated with small and large spin polarizations. It is found that with small spin polarization, the transverse (longitudinal) spin relaxation is divided into four (two) regimes: the normal weak scattering regime, the anomalous D'yakonov-Perel'-like regime, the anomalous Elliott-Yafet-like regime, and the normal strong scattering regime (the anomalous Elliott-Yafet-like regime and the normal strong scattering regime). With large spin polarization, we find that the Hartree-Fock self-energy, which acts as an effective magnetic field, can markedly suppress the transverse spin relaxation in both weak and strong scattering limits. Moreover, by noting that as both the momentum relaxation time and the Hartree-Fock effective magnetic field vary with the scattering length in cold atoms, the anomalous D'yakonov-Perel'-like regime is suppressed and the transverse spin relaxation is hence divided into three regimes in the scattering length dependence: the normal weak scattering regime, the anomalous Elliott-Yafet-like regime, and the strong scattering regime. On the other hand, the longitudinal spin relaxation is again divided into the anomalous Elliott-Yafet-like and normal strong scattering regimes. Furthermore, it is found that the longitudinal spin relaxation can be either enhanced or suppressed by the Hartree-Fock effective magnetic field if the spin polarization is parallel or antiparallel to the effective Zeeman magnetic field.

Measurements on spin relaxation time in superfluid

^{3}\mathit{A}_{1}

were carried out at a pressure of 22.4 bar and a static field of 7.5 kG. The influence of surface coverage by

^{4}\mathrm{He}

was systematically explored. The

^{4}\mathrm{He}

coverage is used to eliminate the spin relaxation at the boundary walls and to extract the spin relaxation time in the warmer half of bulk

{\mathit{A}}_{1}

phase. The bulk spin relaxation time is much shorter than expected from Leggett-Takagi theory applied to the

{\mathit{A}}_{1}

phase. In the colder half of the phase,

^{4}\mathrm{He}

coverage anomalously has no effect on the spin relaxation time.