Optically rewritable patterns of nuclear magnetization in gallium arsenide

Abstract

The control of nuclear spin polarization is important to the design of materials and algorithms for spin-based quantum computing and spintronics. Towards that end, it would be convenient to control the sign and magnitude of nuclear polarization as a function of position within the host lattice. Here we show that, by exploiting different mechanisms for electron -nuclear interaction in the optical pumping process, we are able to control and image the sign of the nuclear polarization as a function of distance from an irradiated GaAs surface. This control is achieved using a crafted combination of light helicity, intensity and wavelength, and is further tuned via use of NMR pulse sequences. These results demonstrate all-optical creation of micron scale, rewritable patterns of positive and negative nuclear polarization in a bulk semiconductor without the need for ferromagnets, lithographic patterning techniques, or quantum-confi ned structures.

Sensitive magnetic control of ensemble nuclear spin hyperpolarization in diamond

“…In addition to the high magnetic field, the experiment requires cryogenic temperatures to attenuate competing spin-lattice relaxation processes, and it relies upon strong microwave irradiation near the electron precession frequency to accomplish polarization transfer. In alternative incarnations of this experiment that have been less generally applied, the initial electron polarization is produced by an optical pumping cycle involving the spin-orbit coupling 16 in a suitable substrate; the subsequent nuclear polarization can be controlled by electrical current in certain semiconductors and at cryogenic temperatures [17][18][19] .…”

Near-band-gap photoinduced nuclear spin dynamics in semi-insulating GaAs: Hyperfine- and quadrupolar-driven relaxation

“…This sample belongs to a lot identical to that used in prior studies: [17][18][19][20][21] It has resistivity greater than 10 7 cm, mobility greater than 6000 cm 2 /(V s), and the surface orientation is [100]. Secondary ion beam spectrometry (SIMS) data reveal the presence of S impurities at a concentration of 7 × 10 14 ; other impurities including H, C, O, Si, Cr, Mn, and Fe are either absent or below the SIMS detection limit.…”

“…As long recognized, this channel of nuclear spin relaxation is key to inducing helicity-dependent nuclear spin order, and thus forms the foundation of OPNMR. 22 More recently a second mechanism was proposed 23 and verified experimentally 20,21 whereby fluctuating electric field gradients in the vicinity of the intermittently photoelectron-occupied defects lead to nuclear spin relaxation via quadrupolar interactions. Such fluctuations are inherently insensitive to light helicity, such that quadrupolar relaxation always drives the nuclear spin ensemble towards equilibrium at the applied magnetic field and temperature.…”

“…Such fluctuations are inherently insensitive to light helicity, such that quadrupolar relaxation always drives the nuclear spin ensemble towards equilibrium at the applied magnetic field and temperature. As shown previously 20,21 the dominating mechanism can be experimentally dictated using, for example, laser light intensity to change the fractional photoelectron occupation of the defect site to a higher value (driving hyperfine-mediated optical pumping) or to a lower value (driving quadrupolar relaxation to thermal equilibrium).…”

Manipulation of a Nuclear Spin by a Magnetic Domain Wall in a Quantum Hall Ferromagnet

“…There is currently a great interest in nuclear spintronics – developing means of storing and manipulating information using nuclear spins in solids123456789101112131415. A major progress has been achieved recently by experimentally demonstrating electrical detection and manipulation of nuclear spins with spins of electrons in quantum Hall systems101112131415161718192021222324.…”