Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session D8: Focus Session: Spin-Dependent Phenomena in Semiconductors: Nitrogen Vacancies in Diamond and Nuclear Spins |
Hide Abstracts |
Sponsoring Units: GMAG DMP FIAP Chair: Hanan Dery, University of Rochester Room: 104 |
Monday, March 3, 2014 2:30PM - 2:42PM |
D8.00001: Increasing NV center density by shallow $^{12}$C implantation in N delta-doped diamond K. Ohno, B.A. Myers, B.J. Aleman, C.A. McLellan, A.C. Bleszynski Jayich, D.D. Awschalom Scalable creation of solid-state single spins is important to nanoscale sensing. Nitrogen-vacancy (NV) centers created by the N delta-doping technique display long \textit{T}$_{2}$ at depths $<$100 nm [1] which were exploited to demonstrate nm-scale nuclear magnetic resonance.[2] One issue of this technique is the low NV density, which prevents their incorporation into diamond nanostructures. This is caused by poor depth localization of vacancies by post growth electron irradiation. Here we use shallow $^{12}$C implantation to localize them. By controlling annealing time and temperature, shallow vacancies diffuse into the N doped layer to selectively activate doped NV centers. We observe NV densities 10 times greater than in irradiated samples. Resulting NV centers display \textit{T}$_{2}$ $>$ 500 $\mu$s, suggesting C implantation damage to the N doped layer is minimized. The enhanced NV density is used to demonstrate NV center localization in a small volume. We find an average of 1.3 NVs confined to a volume of 150 nm in diameter and 50 nm in depth within an array of EB lithographically patterned pillars, useful for single photon sources and scanning probe based sensing. [1] K. Ohno et al., Appl. Phys. Lett. 101, 082413(2012). [2] H. J. Mamin et al., Science 339, 557(2013). [Preview Abstract] |
Monday, March 3, 2014 2:42PM - 2:54PM |
D8.00002: Mitigating surface-induced decoherence of spin sensors in nitrogen delta-doped diamond Bryan A. Myers, Matthieu C. Dartiailh, Kenichi Ohno, David D. Awschalom, Ania C. Bleszynski Jayich The negatively-charged nitrogen-vacancy (NV) center in diamond is a robust nanoscale sensor of magnetic fields. To maximize their sensitivity to external spins, NVs have to be located close to the diamond surface while mitigating surface-induced decoherence. This requires a quantitative understanding of the dominant noise origins, which are currently not well understood. To address this we create shallow NVs by delta-doping during CVD growth [1] and apply scanning probe-based magnetic resonance imaging to find their depths with nm precision. We probe the noise with dynamical decoupling (DD) control of the NVs and fit their coherence decay envelopes to a spin-bath model with two contributions: bulk and surface electronic spins. The fits yield a surface spin density $\sigma_{\mathrm{s}} =$ 0.0032/nm$^{2}$ and relaxation rate 1/$\tau_{\mathrm{s}} =$ 190 kHz. We find an optimal CPMG-4 passive detection sensitivity of 250 $\mu _{\mathrm{p}}$/$\surd $Hz for an NV at 14 nm depth. Doped NVs within 10 nm of the surface were progressively decoupled from noise in the 1/$\tau _{\mathrm{s}}$ frequency regime using shorter DD inter-pulse delays, thereby enhancing their sensitivity. \\[4pt] [1] K. Ohno et al., Appl. Phys. Lett. 101, 082413 (2012). [Preview Abstract] |
Monday, March 3, 2014 2:54PM - 3:06PM |
D8.00003: Theory of feedback cooling of nuclear spins in diamond nitrogen-vacancy center Ping Wang, Wen Yang We develop a microscopic theory for the feedback cooling of nuclear spins in the diamond nitrogen-vacancy center at low temperature. By adiabatically eliminating the fast motion of the NV center, we derive an analytical rate equation to describe the dynamics of the nitrogen and $^{13}$C nuclei. This equation is solved both numerically and analytically using the Fokker-Planck equation. The results provide a good explanation to the recently observed nitrogen and $^{13}$C nuclear spin cooling in nitrogen-vacancy center by coherent population trapping [E. Togan \textit{et al}., Nature 478, 497 (2011)]. They also suggest an optimal pumping power for optimcal cooling effect. [Preview Abstract] |
Monday, March 3, 2014 3:06PM - 3:42PM |
D8.00004: Nanoscale magnetic imaging of individual electron spins under ambient conditions Invited Speaker: Michael Grinolds The detection of ensembles of spins under ambient conditions has revolutionized the biological, chemical, and physical sciences through magnetic resonance imaging and nuclear magnetic resonance. Pushing sensing capabilities to the individual-spin level would enable unprecedented applications such as single molecule structural imaging; however, the weak magnetic fields from single spins are undetectable by conventional methods. Recently, there has been significant theoretical and experimental research into using nitrogen-vacancy (NV) defect centers in diamond as a new type of magnetometer capable of detecting individual spins. In this talk I present measurements using such an NV-based magnetometer to detect and image the magnetic fields from individual electron spins under ambient conditions. Magnetic imaging is achieved by either spatially mapping a target spin's magnetic field using a scanning magnetometer [1], or by performing magnetic resonance imaging via scanning magnetic field gradients. These results in imaging individual electron spins makes NV-based magnetometry immediately applicable to diverse systems including imaging spin chains, readout of individual spin-based quantum bits, and determining the precise location of spin labels in biological systems. \\[4pt] [1] M.S. Grinolds \textit{et al.} Nature Physics, 9 215-219 (2013). [Preview Abstract] |
Monday, March 3, 2014 3:42PM - 3:54PM |
D8.00005: Study of a single nitrogen-vacancy center in diamond to detect surrounding electron spins Chathuranga Abeywardana, Viktor Stepanov, Susumu Takahashi A nitrogen-vacancy (NV) center in diamond is a promising candidate for applications of nanoscale magnetic sensing as well as for investigation of fundamental quantum sciences because of its unique properties including capability to detect a NV center, long decoherence time even at room temperature, stable fluorescence and biocompatibility. Here we will present our approach to use a single NV center in diamond to probe tiny magnetic fields ($\sim$ uT or less) due to surrounding spin environments. We will discuss magnetic field dependence of spin decoherence in a single NV center as well as use of double electron-electron resonance spectroscopy to detect surrounding electron spins. [Preview Abstract] |
Monday, March 3, 2014 3:54PM - 4:06PM |
D8.00006: Nitrogen vacancy centers for nanoscale magnetic field mapping of micromagnets David Roy-Guay, Andreas Ruediger, Julien Plathier, Lilian Childress, Denis Morris, Michel Pioro-Ladri\`ere Nitrogen vacancy (NV) centers in diamond are nanoscale color centers with a long spin coherence time ($\sim$ 1 ms) even at room temperature (RT). Combined with the option of optical readout of a microwave-addressable state, NV centers in diamond are outstanding magneto-,electro-, or thermometers which allow for the creation of high spatial resolution nano-sensors [1]. In this work, we report on our first RT Rabi oscillations at 0.7 MHz of an ensemble of NV centers and preliminary results on an optically detected Stark shift of a single NV center. Fabrication by reactive ion etching of an array of NV nanodetectors for magnetic field mapping will also be presented. The array is mapped with a confocal photoluminescence setup to determine the NV density per pillar. Subsequent patterning of local gates will allow for high electric fields as a tuning parameter to enhance the magnetic field sensitivity of the NV array, resulting in a high precision magnetometer without the use of spin-echo sequences. Such a magnetic CCD is a promising tool to map local magnetic fields produced by micromagnets, such as those used in spin qubit architectures for fast qubit gates [2]. \\[4pt] [1] Dolde, F. et al. Nat. Phys. 7, 459-463 (2011) \\[0pt] [2] Pioro-Ladri\`{e}re, M. et al. Nat. Phys. 4, 776-779 (2008) [Preview Abstract] |
Monday, March 3, 2014 4:06PM - 4:18PM |
D8.00007: The effect of spin transport on lifetime in nanoscale systems Jeremy Cardellino, Nicolas Scozzaro, Michael Heman, Andrew Berger, Chi Zhang, Kin Chung Fong, Ciriyam Jayaprakash, Denis Pelekhov, Chris Hammel Spin transport electronics utilizes electron spin as a state variable for information processing and storage. This requires manipulation of spin ensembles for data encoding, and spin transport for information transfer. Here we report spatially resolved magnetic resonance studies of electron spin ensembles confined to a quasi 1D `spin nanowire' formed by nitrogen ion implantation in diamond. We obtain the ensemble spin lifetime, that is, spin autocorrelation time, by measuring statistical fluctuations of the net moment ($\surd $N \textless 100 net spins), which is in thermal equilibrium and has no imposed polarization gradient. We find the lifetime of the ensemble is dominated by spin transport from the ensemble into an adjacent reservoir, which is in striking contrast to conventional spin-lattice relaxation measurements of isolated spin ensembles. In addition, using a novel spin manipulation protocol, we demonstrate spectroscopic measurements on nanoscale spin ensembles that corroborate spin transport in strong field gradients. Our experiments, supported by microscopic Monte Carlo modelling, provide a unique insight into the intrinsic dynamics of charge-motion-free spin currents needed for nanoscale devices which seek to control spins. [Preview Abstract] |
Monday, March 3, 2014 4:18PM - 4:30PM |
D8.00008: Impurities and electron spin relaxations in nanodiamonds studied by multi-frequency electron spin resonance Franklin Cho, Susumu Takahashi Nano-sized diamond or nanodiamond is a fascinating material for potential applications of fluorescence imaging and magnetic sensing of biological systems via nitrogen-vacancy defect centers in diamonds. Sensitivity of the magnetic sensing strongly depends on coupling to surrounding environmental noises, thus understanding of the environment is critical to realize the application. In the present study, we employ multi-frequency (X-band, 115 GHz and 230 GHz) continuous-wave (cw) and pulsed electron spin resonance (ESR) spectroscopy to investigate impurity contents and spin relaxation properties in various sizes of nanodiamonds. Spectra taken with our home-built 230/115 GHz cw/pulsed ESR spectrometer shows presence of two major impurity contents; single substitutional nitrogen impurities (P1) also common in bulk diamonds and paramagnetic impurities (denoted as X) unique to nanodiamonds. The ESR measurement also shows a strong dependence of the population ratio between P1 and X on particle size. Furthermore, we will discuss the nature of spin-lattice relaxation time $T_{1}$ of nanodiamonds studied by pulsed ESR measurements at X-band, 115 GHz and 230 GHz. [Preview Abstract] |
Monday, March 3, 2014 4:30PM - 4:42PM |
D8.00009: Coupling ZnSe band spin states and 4H-SiC defect spin states across their interface Andrew L. Yeats, Anthony Richardella, Nitin Samarth, David D. Awschalom Point defects in silicon carbide (SiC) have emerged as a promising platform for quantum information processing and nanoscale sensing in a technologically-mature semiconductor. ZnSe is a promising candidate for semiconductor spintronic applications and has selection rules compatible with optical orientation of conduction electron spins. We combine pump-probe optical measurements with pulsed optically detected magnetic resonance (ODMR) sequences to investigate coupling between SiC defect spins and ZnSe conduction electron spins in ZnSe/4H-SiC heterostructures. Preparation of these structures by molecular beam epitaxy (MBE) and ion implantation is discussed in terms of interface optimization. [Preview Abstract] |
Monday, March 3, 2014 4:42PM - 4:54PM |
D8.00010: Nuclear Spin Polarization of Phosphorus Donors in Silicon. Direct Evidence from 31P-Nuclear Magnetic Resonance Patryk Gumann, Chandrasekhar Ramanathan, Om Patange, Osama Moussa, Mike Thewalt, Helge Riemann, Nikolay Abrosimov, Peter Becker, Hans-Joachim Pohl, Kohei Itoh, David G. Cory We experimentally demonstrate the optical hyperpolarization and coherent control of $^{31}$P, nuclear spins in single crystal silicon via the inductive readout of the nuclear magnetic resonance (NMR) signal of $^{31}$P at a concentration of 1.5 x 10$^{15}$ cc$^{-1}$. The obtained polarization is sufficient the $^{31}$P spin polarization of 1.17 x 10$^{15}$ in a 10 mm x 10 mm sample, observed in one FID with signal-to-noise ration of 113. The linewidth is 800 Hz. The Hahn echo pulse sequence reveals a $^{31}$P T$_{2}$ time of 0.42 s at 1.6 K, which was extended by the Carr Purcell cycle to 1.2 s at the same temperature. The maximum build-up of the nuclear polarization was achieved within $\sim$577 seconds, at 4.2 K, in 6.7 T, using optical excitations provided by an infra-red laser. [Preview Abstract] |
Monday, March 3, 2014 4:54PM - 5:06PM |
D8.00011: Hyperpolarization of $^{29}$Si by Resonant Nuclear Spin Transfer from Optically Hyperpolarized $^{31}$P Donors Phillip Dluhy, Jeff Salvail, Kamyar Saeedi, Mike Thewalt, Stephanie Simmons Recent developments in nanomedicine have allowed nanoparticles of silicon containing hyperpolarized $^{29}$Si to be imaged in vivo using magnetic resonance imaging. The extremely long relaxation times and isotropy of the Si lattice make polarized $^{29}$Si isotopes ideal for these sorts of imaging methods. However, one of the major difficulties standing in the path of widespread adoption of these techniques is the slow rate at which the $^{29}$Si is hyperpolarized and the limited maximum hyperpolarization achievable. In this talk, I will describe an effective method for hyperpolarization of the $^{29}$Si isotopes using resonant optical pumping of the donor bound exciton transitions to polarize the $^{31}$P donor nuclei, and a choice of static magnetic field that conserves energy during spin flip flops between donor nuclear and $^{29}$Si spins to facilitate diffusion of this polarization. Using this method, we are able to polarize greater than 10\% of the $^{29}$Si centers in 64 hours without seeing saturation of the $^{29}$Si polarization. [Preview Abstract] |
Monday, March 3, 2014 5:06PM - 5:18PM |
D8.00012: Dynamic nuclear polarization from current-induced electron spin polarization in n-InGaAs Christopher Trowbridge, Benjamin Norman, Yuichiro Kato, David Awschalom, Vanessa Sih Control of the nuclear spin system could prove useful for applications in spintronics or spin-based quantum computation for intermediate term data storage and for the suppression of electron spin dephasing resulting from hyperfine coupling. We investigate the role of nuclear spins in materials with electrically generated spin polarization. The electron spin polarization generated by electrical current in a non-magnetic semiconductor is transferred via dynamic nuclear polarization to the nuclei. The resulting nuclear field is interrogated using Larmor magnetometry. We measure the nuclear field as a function of applied magnetic field, current magnitude and direction, and temperature. An unexpected spatial asymmetry in saturated nuclear field is found. The direction of the nuclear polarization is determined by the directions of the electron spin alignment and external magnetic field, allowing electronic control over the sign of the nuclear alignment direction. Careful study of the nuclear field also enables characterization of the current-induced electron spin polarization in situations that are otherwise experimentally inaccessible. Work supported by AFOSR, NSF and ONR. [Preview Abstract] |
Monday, March 3, 2014 5:18PM - 5:30PM |
D8.00013: Electronic structure of CrN/MgO multilayers Antia S. Botana, Victor Pardo, Daniel Baldomir, Peter Blaha The changes in the electronic structure of oxides and other correlated compounds caused by electronic reconstructions at their surface and interfaces has attracted much attention recently. CrN shows a magnetostructural phase transition as a function of temperature and controversial electronic properties. In the bulk, calculations show that with the onset of magnetism CrN is semiconducting but being very close to a metal-insulator transition. For free standing thin films with increasing thickness the gap closes and conducting states appear connected with a structural relaxation at the surface, where an electric dipole is formed. We report a series of electronic structure calculations for CrN/MgO multilayers within the LDA+U method. In contrast to the free CrN surface, CrN grown on MgO retains the semiconducting behavior shown in the bulk and even widens its band gap as the CrN thickness is reduced. Otherwise, interfacial effects with the oxide lead to negligible electronic reconstructions. The d-levels of the interfacial Cr atoms are lowered in energy due to the different environment present at the interface. The evolution of the transport properties is analyzed and a significant enhancement of the Seebeck coefficient is predicted for the case of very thin CrN layers. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700