APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

10 Jul 2006

Volume 89, Issue 2, Articles (02xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 89, 023901 (2006); http://dx.doi.org/10.1063/1.2219984 (3 pages)

Nikhil Ganesh, Ian D. Block, and Brian T. Cunningham
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

High temperature ferromagnetism in Ni-doped In2O3 and indium-tin oxide

Germanas Peleckis, Xiaolin Wang, and Shi Xue Dou

Appl. Phys. Lett. 89, 022501 (2006); http://dx.doi.org/10.1063/1.2220529 (3 pages) | Cited 33 times

Online Publication Date: 10 July 2006

Full Text: Read Online (HTML) | Download PDF


See Also: Publisher's Note

Show Abstract
Observation of high temperature ferromagnetism in Ni-doped In2O3 and indium-tin-oxide (ITO) samples prepared by a solid state synthesis route is reported. Both Ni-doped compounds showed a clear ferromagnetism above 300 K with the magnetic moments of 0.03–0.06μB/Ni and 0.1μB/Ni at 300 and 10 K, respectively. Ni-doped In2O3 samples showed a typical semiconducting behavior with a room temperature resistivity of ρ ∼ 2 Ω cm, while Ni-doped ITO samples were metallic with ρ ∼ 2×10−2 Ω cm. Analysis of different conduction mechanisms suggested that variable range hopping model explains our ρ-T data for the Ni-doped In2O3 sample the best.
Show PACS
75.50.Pp Magnetic semiconductors
75.50.Dd Nonmetallic ferromagnetic materials
61.72.up Other materials
75.30.Cr Saturation moments and magnetic susceptibilities
72.20.Ee Mobility edges; hopping transport
72.80.Jc Other crystalline inorganic semiconductors

Interface electronic structure in MnAs on GaAs (001) studied by in situ photoemission spectroscopy

J. Okabayashi, K. Kanai, K. Kubo, S. Toyoda, M. Oshima, K. Ono, and J. Yoshino

Appl. Phys. Lett. 89, 022502 (2006); http://dx.doi.org/10.1063/1.2217256 (3 pages) | Cited 4 times

Online Publication Date: 10 July 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the relationship between surface morphology and electronic structure of MnAs on GaAs (001) depending on the MnAs layer thickness using in situ photoemission spectroscopy. For less than 4 ML (monolayer) growth of MnAs, metallic and ferromagnetic properties were not observed due to the island growth. Valence-band photoemission spectra revealed that the localized Mn 3d states for less than 4 ML growth gradually change to the itinerant characteristics with increasing MnAs layer thickness. Core-level photoemission spectra have revealed that the Ga atoms are not segregated onto the surface and an abrupt interface is identified.
Show PACS
73.20.At Surface states, band structure, electron density of states
79.60.Bm Clean metal, semiconductor, and insulator surfaces
68.35.B- Structure of clean surfaces (and surface reconstruction)

Mn3Sn2: A promising material for magnetic refrigeration

T. Mazet, H. Ihou-Mouko, and B. Malaman

Appl. Phys. Lett. 89, 022503 (2006); http://dx.doi.org/10.1063/1.2220541 (3 pages) | Cited 17 times

Online Publication Date: 10 July 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Mn3Sn2 presents two second-order magnetic transitions of ferromagnetic origin at TC1 ∼ 262 K and TC2 ∼ 227 K. Both transitions give peaks of similar magnitude (ΔSMmax ∼ 27 mJ cm−3 K−1 for ΔH = 5 T) in the temperature dependence of the magnetic entropy change yielding an anomalous magnetocaloric response approaching that of a two-component hybrid material. Its refrigerant capacity of ∼ 1.1 J cm−3 (ΔH = 5 T) for an optimal reversible cycle with cold and hot ends at ∼ 220 and ∼ 280 K is about half that of the best known magnetic refrigerants working around room temperature. However, Mn3Sn2 possess several advantages making it a promising candidate for magnetic refrigeration applications: (i) it has a large temperature span with a roughly constant ΔSM, (ii) it is not subjected to hysteresis losses, and (iii) it is made from low-cost and nontoxic elements.
Show PACS
75.50.Dd Nonmetallic ferromagnetic materials
75.30.Sg Magnetocaloric effect, magnetic cooling
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)

Giant magnetoresistance in an all-oxide spacerless junction

M. P. Singh, B. Carvello, and L. Ranno

Appl. Phys. Lett. 89, 022504 (2006); http://dx.doi.org/10.1063/1.2219413 (3 pages) | Cited 10 times

Online Publication Date: 10 July 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the fabrication of an oxide-specific type of magnetoresistive junction, which is a ferromagnetic bilayer. Both electrodes are high spin-polarization oxides: magnetite (Fe3O4) and manganite (La0.7Sr0.3MnO3). Negligible magnetic coupling between both ferromagnetic electrodes is realized, which allows us to obtain parallel and antiparallel magnetic configurations of the electrodes when sweeping the applied magnetic field. The structure exhibits negative giant magnetoresistance (GMR) at low temperatures. This negative MR shows that both electrodes stay spin polarized at the interface and have opposite spin polarizations, i.e., the Fe3O4 layer has a negative spin polarization at low temperature. Maximum GMR (−5%) is obtained at 55 K.
Show PACS
75.47.De Giant magnetoresistance
75.50.Dd Nonmetallic ferromagnetic materials
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)

Huge nonequilibrium magnetoresistance in hybrid superconducting spin valves

Francesco Giazotto, Fabio Taddei, Rosario Fazio, and Fabio Beltram

Appl. Phys. Lett. 89, 022505 (2006); http://dx.doi.org/10.1063/1.2220001 (3 pages) | Cited 4 times

Online Publication Date: 11 July 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A hybrid ferromagnet-superconductor spin valve is proposed. Its operation relies on the interplay between nonequilibrium transport and proximity-induced exchange coupling in superconductors. Huge tunnel magnetoresistance values as large as ∼ 106% can be achieved in suitable ferromagnet-superconductor combinations under proper voltage biasing. The controllable spin-filter nature of the structure combined with its intrinsic simplicity makes this setup attractive for low-temperature spintronic applications where reduced power dissipation is an additional requirement.
Show PACS
74.45.+c Proximity effects; Andreev reflection; SN and SNS junctions
74.50.+r Tunneling phenomena; Josephson effects
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Et Exchange and superexchange interactions
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
85.25.-j Superconducting devices

L10 FePt films deposited on pyramid-type Si substrate for perpendicular magnetic recording media

C. L. Zha, B. Ma, Z. Z. Zhang, T. R. Gao, F. X. Gan, and Q. Y. Jin

Appl. Phys. Lett. 89, 022506 (2006); http://dx.doi.org/10.1063/1.2221389 (3 pages) | Cited 7 times

Online Publication Date: 11 July 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Tetragonal L10 FePt films are deposited on the pyramid-type Si substrates fabricated by chemical etching process from (100) Si wafers. The films are composed of different easy-axis orientation FePt grains, most of which with the easy axis along substrate normal, the others with the easy axis tilted from the normal direction. When the magnetic field is applied along the perpendicular direction, the easy-axis tilted grains reverse first, and then the magnetization reversal of the whole film is promoted. Small coercivity, suitable α, and high squareness are obtained. And the coercivity increases when the applied field is tilted from the normal direction.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Ss Magnetic recording materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.60.Jk Magnetization reversal mechanisms
81.65.Cf Surface cleaning, etching, patterning

Improved oxygen diffusion model to explain the effect of low-temperature baking on high field losses in niobium superconducting cavities

Gianluigi Ciovati

Appl. Phys. Lett. 89, 022507 (2006); http://dx.doi.org/10.1063/1.2220059 (3 pages) | Cited 10 times

Online Publication Date: 13 July 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Radio-frequency (rf) superconducting cavities made of high purity niobium are widely used to accelerate charged particle beams in particle accelerators. The major limitation to achieve rf field values approaching the theoretical limit for niobium is represented by “anomalous” losses which degrade the quality factor of the cavities starting at peak surface magnetic fields of about 100 mT, in the absence of field emission. These high field losses are often referred to as Q drop. It has been observed that the Q drop is drastically reduced by baking the cavities at 120 °C for about 48 h under ultrahigh vacuum. An improved oxygen diffusion model for the niobium-oxide system is proposed to explain the benefit of the low-temperature baking on the Q drop in niobium superconducting rf cavities. The model shows that baking at 120 °C for 48 h allows oxygen to diffuse away from the surface, and therefore increasing the lower critical field towards the value for pure niobium.
Show PACS
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.25.F- Transport properties
74.25.Ha Magnetic properties including vortex structures and related phenomena
74.25.Op Mixed states, critical fields, and surface sheaths

Room temperature ferromagnetism in two-step-prepared Co-doped ZnO bulks

T. Zhu, W. S. Zhan, W. G. Wang, and John Q. Xiao

Appl. Phys. Lett. 89, 022508 (2006); http://dx.doi.org/10.1063/1.2221881 (3 pages) | Cited 20 times

Online Publication Date: 14 July 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have prepared Co-doped ZnO bulks with a two-step method. The bulk samples are sintered at the temperature above 1000 °C to get pure single phase and then treated by Zn vapor in a vacuum. Based on such two-step preparation, clear carrier induced ferromagnetism is found in Zn treated Co-doped ZnO bulks, which suggests that the magnetism mechanism can be of codoping effect. The onset of ferromagnetism is associated with the further increase of the hybridization of the impurity band with 3d states near the Fermi level when additional carrier induced to let the Stoner criterion for ferromagnetism to be satisfied.
Show PACS
75.50.Dd Nonmetallic ferromagnetic materials
75.50.Pp Magnetic semiconductors
61.72.uj III-V and II-VI semiconductors
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
71.55.Gs II-VI semiconductors
71.20.Nr Semiconductor compounds

Growth of epitaxial thin films of the ordered double perovskite La2NiMnO6 on different substrates

H. Guo, J. Burgess, S. Street, A. Gupta, T. G. Calvarese, and M. A. Subramanian

Appl. Phys. Lett. 89, 022509 (2006); http://dx.doi.org/10.1063/1.2221894 (3 pages) | Cited 39 times

Online Publication Date: 14 July 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Epitaxial thin films of La2NiMnO6, a ferromagnetic semiconductor, have been fabricated on different substrates by pulsed laser deposition. The x-ray diffraction and Raman scattering observations reveal that the films are single crystalline and have an orthorhombic structure. The magnetic properties of the films, including the coercive field, remanent magnetization, and Curie temperature, are strongly dependent on the choice of the substrate. The optimized films exhibit a magnetic moment of 4.63μB/f.u. at 5 K, with a Curie temperature close to 280 K. The film characteristics are promising for potential device applications in information storage, spintronics, and sensors.
Show PACS
81.05.Hd Other semiconductors
75.70.Ak Magnetic properties of monolayers and thin films
81.15.Fg Pulsed laser ablation deposition
68.55.A- Nucleation and growth
68.55.-a Thin film structure and morphology
75.50.Pp Magnetic semiconductors

Low-frequency vortex dynamic susceptibility and relaxation in mesoscopic ferromagnetic dots

K. Yu. Guslienko

Appl. Phys. Lett. 89, 022510 (2006); http://dx.doi.org/10.1063/1.2221904 (3 pages) | Cited 31 times

Online Publication Date: 14 July 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Vortex dynamics in a restricted geometry is considered for a magnetic system consisting of ferromagnetic cylindrical dots. To describe the vortex dynamic susceptibility and relaxation the equation of motion for the vortex center position is applied. The dependencies of the vortex dynamic susceptibility and resonance linewidth on geometrical parameters are calculated. A method of extracting damping parameter from the vortex low-frequency resonance peaks is proposed and applied for interpretation of resonance data on FeNi circular dots.
Show PACS
75.50.Bb Fe and its alloys
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)

Magnetic tunnel junctions based on CrO2/SnO2 epitaxial bilayers

G. X. Miao, P. LeClair, A. Gupta, G. Xiao, M. Varela, and S. Pennycook

Appl. Phys. Lett. 89, 022511 (2006); http://dx.doi.org/10.1063/1.2216109 (3 pages) | Cited 12 times

Online Publication Date: 14 July 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Magnetic tunnel junctions were fabricated using thin films of the half-metallic ferromagnet CrO2, employing SnO2 tunnel barriers. Heteroepitaxial CrO2/SnO2 bilayers were grown on (100)-TiO2 substrates via chemical vapor deposition. X-ray diffraction and transmission electron microscopy confirmed heteroepitaxy. A polycrystalline cobalt film forms the top magnetic electrode, yielding CrO2(001)/SnO2(001)/Co structures after patterning. Tunneling magnetoresistances (TMR) up to +14% at 10 K were observed. The sign of the TMR reverses for barrier thicknesses <1 nm, attributed to tunneling being dominated by Co-3d states at low thicknesses and Co-4s states at larger thicknesses.
Show PACS
75.47.Pq Other materials
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
75.50.Dd Nonmetallic ferromagnetic materials
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.37.Lp Transmission electron microscopy (TEM)
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close