Coherent manipulation of nuclear spins using spin injection from a half-metallic spin source

The electronic structures of Co-based Heusler alloys with nonstoichiometric atomic compositions as well as those at the interface of semiconductor junctions are investigated using first principles band calculations. It is shown that the electronic structure of a Co-based Heusler alloy is half-metallic, even for nonstoichiometric but Co-rich compositions, whereas the half-metallicity is lost for Co-poor compositions. It is also shown that magnetic moments at the interface of Co2MnSi/ Si junctions are sensitive to the growth direction and interface structure of the junctions. Efficient spin-injection into Si can be achieved by using a (111)-oriented Co-rich Heusler alloy and controlling the layer-by-layer stacking sequence at the interface.

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Spin-injection device prospects for half-metallic Fe3O4:Al0.1Ga0.9As interfaces

Journal of Applied Physics ◽

10.1063/1.3462435 ◽

2010 ◽

Vol 108 (3) ◽

pp. 034507 ◽

Cited By ~ 8

Author(s):

R. Mansell ◽

J.-B. Laloë ◽

S. N. Holmes ◽

P. K. J. Wong ◽

Y. B. Xu ◽

...

Keyword(s):

Spin Injection ◽

Injection Device ◽

Half Metallic

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COMPARATIVE STUDY OF SPIN INJECTION AND TRANSPORT IN Alq3 AND Co–PHTHALOCYANINE-BASED ORGANIC SPIN VALVES

SPIN ◽

10.1142/s2010324714400098 ◽

2014 ◽

Vol 04 (02) ◽

pp. 1440009 ◽

Cited By ~ 11

Author(s):

SAYANI MAJUMDAR ◽

SUKUMAR DEY ◽

HANNU HUHTINEN ◽

JOHNNY DAHL ◽

MARJUKKA TUOMINEN ◽

...

Keyword(s):

Single Molecule ◽

Giant Magnetoresistance ◽

Chemical Reactivity ◽

Spin Injection ◽

Spin Valve ◽

Spin Valves ◽

Half Metallic ◽

High Expectations ◽

Spacer Layer ◽

Spin Polarized

Recent experimental reports suggest the formation of a highly spin-polarized interface ("spinterface") between a ferromagnetic (FM) Cobalt ( Co ) electrode and a metal-phthalocyanine (Pc) molecule. Another report shows an almost 60% giant magnetoresistance (GMR) response measured on Co / H 2 Pc -based single molecule spin valves. In this paper, we compare the spin injection and transport properties of organic spin valves with two different organic spacers, namely Tris(8-hydroxyquinolinato) aluminum ( Alq 3) and CoPc sandwiched between half-metallic La 0.7 Sr 0.3 MnO 3 (LSMO) and Co electrodes. Alq 3-based spin valves exhibit clear and reproducible spin valve switching with almost 35% negative GMR at 10 K, in accordance with previous reports. In contrast, cobalt-pthalocyanine ( CoPc )-based spin valves fail to show clear GMR response above noise level despite high expectations based on recent reports. Investigations of electronic, magnetic and magnetotransport properties of electrode/spacer interfaces of LSMO/ CoPc / Co devices offer three plausible explanations for the absence of GMR: (1) CoPc films are strongly chemisorbed on the LSMO surface. This improves the LSMO magnetic properties but also induces local traps at the LSMO interface for spin-polarized charge carriers. (2) At the Co / CoPc interface, diffusion of Co atoms into the organic semiconductor (OS) layer and chemical reactivity between Co and the OS deteriorates the FM properties of Co . This renders the Co / CoPc interface as unsuitable for efficient spin injection. (3) The presence of heavy Co atoms in CoPc leads to large spin–orbit coupling in the spacer. The spin relaxation time in the CoPc layer is therefore considerably smaller compared to Alq 3. Based on these findings, we suggest that the absence of GMR in CoPc -based spin valves is caused by a combined effect of inefficient spin injection from FM contacts and poor spin transport in the CoPc spacer layer.

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Manipulation of nuclear spins in GaAs using a half-metallic spin source of Co2MnSi

2015 IEEE Magnetics Conference (INTERMAG) ◽

10.1109/intmag.2015.7156849 ◽

2015 ◽

Author(s):

T. Uemura ◽

M. Yamamoto

Keyword(s):

Nuclear Spins ◽

Half Metallic

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Coherent manipulation of nuclear spins in the breakdown regime of integer quantum Hall states

Journal of Physics Conference Series ◽

10.1088/1742-6596/150/2/022034 ◽

2009 ◽

Vol 150 (2) ◽

pp. 022034 ◽

Cited By ~ 2

Author(s):

M Kawamura ◽

H Takahashi ◽

Y Hashimoto ◽

S Katsumoto ◽

T Machida

Keyword(s):

Quantum Hall ◽

Nuclear Spins ◽

Quantum Hall States ◽

Integer Quantum ◽

Coherent Manipulation ◽

Hall States

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Materials and Device Design with ZnO-Based Diluted Magnetic Semiconductors

MRS Proceedings ◽

10.1557/proc-666-f4.6 ◽

2001 ◽

Vol 666 ◽

Cited By ~ 18

Author(s):

Kazunori Sato ◽

Hiroshi Katayama-Yoshida

Keyword(s):

Diluted Magnetic Semiconductors ◽

Magnetic Semiconductors ◽

Spin Injection ◽

Wide Band ◽

Ferromagnetic State ◽

Hole Doping ◽

Half Metallic ◽

Practical Applications ◽

Doped Zno ◽

Diluted Magnetic

ABSTRACTWe propose a materials design to fabricate the transparent and half-metallic ferromagnets in V-, Cr-, Mn+hole, Fe-, Co-, and Ni-doped ZnO based upon ab initio electronic structure calculation. Mn-doped ZnO is anti-ferromagnetic spin glass state, however, it becomes half-metallic ferromagnets upon hole doping. The ferromagnetic state becomes more stable by electron doping in Fe-, Co- or Ni-doped ZnO. From the point of practical applications, it is feasible to realize the half-metallic ferromagnets with high Curie temperature, because n-type ZnO is easily available. We propose the design of new functional devices, such as spin-FET, photo-induced ferromagnets, and spin-injection devices using negative electron affinity in the wide band gap semiconductors.

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