Browsing by Author "STAMENOV, PLAMEN"
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Cubic Mn 2 Ga Thin films: Crossing the spin gap with ruthenium
COEY, JOHN; VENKATESAN, MUNUSWAMY; RODE, KARSTEN; STAMENOV, PLAMEN (2014)Cubic Mn2Ga films with the half-Heusler C1b structure are grown on V (001) epitaxial films. The phase is a soft ferrimagnet, with Curie temperature TC = 225 K and magnetization Ms=280 kA m−1, equivalent to 1.65μB per ... -
Dependence of charge carrier injection on the interface energy barrier in short-channel polymeric field effect transistors
COEY, JOHN; STAMENOV, PLAMEN (2012)The influence of contact materials on the electrical characteristics of field-effect transistors made from poly(3-hexylthiophene) with short-channel lengths of 80nm is investigated. The thermally activated output current ... -
Dynamic response of ammonia sensors constructed from polyaniline nanofibre films with varying morphology
COEY, JOHN; STAMENOV, PLAMEN (2012)Polyaniline is acid-doped with HCl, HNO3, HClO4, HBr or H2SO4 to yield thin films that are nanofibrous or dense. The nanofibrous films show a faster response to ammonia gas, and the response is greater when the films are ... -
Electron and spin transport studies of gated lateral organic devices
COEY, JOHN; STAMENOV, PLAMEN (2012)In view of the many, often contradictory, reports of magneto-resistance (M R) in spin valve stacks containing a layer of organic semiconductor, mostly of the small molecule variety, we have investigated interdigitated ... -
Exchange-biased magnetic tunnel junctions with antiferromagnetic epsilon-Mn3Ga
RODE, KARSTEN; VENKATESAN, MUNUSWAMY; STAMENOV, PLAMEN; COEY, JOHN (2012)Oriented c-axis films of the hexagonal triangular antiferromagnetic ?-Mn3Ga have been used in bottom-pinned synthetic antiferromagnetmagnetic tunnel junctions with MgO barriers, which show up to 150% tunneling magnetoresistance ... -
Fermi level spin polarization of polycrystalline thulium by point contact Andreev reflection spectroscopy
COEY, JOHN; STAMENOV, PLAMEN (2011)The spin polarization near the Fermi level in bulk polycrystalline ferrimagnetic thulium is investigated by means of point contact Andreev reflection (PCAR), in the temperature interval (1.9?9.2 K). The highest polarization ... -
Ferromagnetism in defect-ridden oxides and related materials
COEY, JOHN; VENKATESAN, MUNUSWAMY; STAMENOV, PLAMEN (2010)The existence of high-temperature ferromagnetism in thin films and nanoparticles of oxides containing small quantities of magnetic dopants remains controversial. Some regard these materials as dilute magnetic semiconductors, ... -
Giant spontaneous Hall effect in zero-moment Mn2Ru x Ga
RODE, KARSTEN; COEY, JOHN; STAMENOV, PLAMEN; BORISOV, KIRIL; LAU, YONG; BETTO, DAVIDE (2015)Spin-dependent transport properties of Mn2Ru x Ga thin-films are studied as function of the Ru concentration and the substrate-induced strain. The large spontaneous Hall angle of 7.7% twenty times bigger than in other 3d ... -
High field magnetotransport and point contact Andreev reflection measurements on CuCr2Se4 and CuCr2Se 3Br - Degenerate magnetic semiconductor single crystals
COEY, JOHN; STAMENOV, PLAMEN (2014)Single crystals of the metallically degenerate fully magnetic semiconductors CuCr2Se4 and CuCr2Se3Br have been prepared by the Chemical Vapour Transport method, using either Se or Br as transport agents. The high-quality, ... -
High spin polarization in epitaxial films of ferrimagnetic Mn3Ga
COEY, JOHN; VENKATESAN, MUNUSWAMY; RODE, KARSTEN; STAMENOV, PLAMEN (2011)Ferrimagnetic Mn3Ga exhibits a unique combination of low saturation magnetization (Ms=0.11 MA m−1) and high perpendicular anisotropy with a uniaxial anisotropy constant of Ku = 0.89 MJ m−3. Epitaxial c-axis films exhibit ... -
Influence of an Au capping layer on the magnetic properties of CoPt nanowires
COEY, JOHN; BYRNE, FIONA; MONZON, LORENA; STAMENOV, PLAMEN; VENKATESAN, MUNUSWAMY (2011)Equiatomic CoPt nanowires with a gold cap layer have been fabricated by electrochemical template synthesis. Au improves the structural and magnetic properties of the L10 ordered CoPt, leading to coercivities of up to 1.43 ... -
Joule Heating Effect on Field-Free Magnetization Switching by Spin-Orbit Torque in Exchange-Biased Systems
STAMENOV, PLAMEN; COEY, JOHN (2017) -
Magnetic and electronic properties of D022-Mn3Ge (001) films
RODE, KARSTEN; SANVITO, STEFANO; COEY, JOHN; STAMENOV, PLAMEN; VENKATESAN, MUNUSWAMY (2012)Oriented thin films of Mn3Ge with the tetragonal D022structure,grown on strontium titanate substrates, exhibit a low magnetization M s?=?73?kA m?1 combined with high uniaxial anisotropyK u?=?0.91?MJ m?3 at 300?K, making ... -
Magnetic, transport, and structural properties of SrRuO3 thin films
STAMENOV, PLAMEN; COEY, JOHN; RODE, KARSTEN (2014)Thin films of the oxide ferromagnetic metal SrRuO3 (SRO) are studied, in view of their potential use within oxide-based spin electronic devices. Here, their epitaxial growth on Si-compatible SrTiO3 substrates is demonstrated ... -
Magnetism in dilute magnetic oxide thin films based on SnO2
STAMENOV, PLAMEN; COEY, JOHN; VENKATESAN, MUNUSWAMY (2006)Thin films of SnO2 prepared by pulsed-laser deposition on R-cut sapphire substrates exhibit ferromagnetic properties at room temperature when they are doped with Cr, Mn, Fe, Co, or Ni, but not with other 3d cations. ... -
Magnetization of electrodeposited nickel: Role of interstitial carbon
STAMENOV, PLAMEN; COEY, JOHN; SANVITO, STEFANO (2006)The magnetization of nickel foils electrodeposited under different conditions was not usually found to differ significantly from that of the bulk (55.4?A?m2?kg?1). However, some galvanostatically deposited films from a ... -
Magnetization Process in Dilute Magnetic Oxides
COEY, JOHN; VENKATESAN, MUNUSWAMY; STAMENOV, PLAMEN (2010)Thin films of dilute magnetic oxides often exhibit high-temperature ferromagnetism with magnetization curves of the form M approximate to M-s tanh(H/H-0); the curves are practically anhysteretic and temperature-independent ... -
Magnetization processes in micron-scale (CoFe/Pt)(n) multilayers with perpendicular anisotropy: First-order reversal curves measured by extraordinary Hall effect
RODE, KARSTEN; COEY, JOHN; STAMENOV, PLAMEN (2012)First-order reversal curves (FORCs) were recorded using the extraordinary Hall effect in micron-sized crosses of [Co90Fe10 (0.5?nm)/Pt (1.0?nm)] n multilayers with n?=?10, 20, and 50, which exhibit perpendicular magnetic ... -
Magnetoresistance of Co-doped ZnO thin films
STAMENOV, PLAMEN; COEY, JOHN; VENKATESAN, MUNUSWAMY (2006)Longitudinal, transverse, and perpendicular magnetoresistances were investigated at temperatures 1.2 T 300 K in fields of up to 20 T for four ZnO films: one undoped, two with 4% Co one paramagnetic, the other exhibiting ... -
Point contact Andreev reflection from semimetallic bismuth-The roles of the minority carriers and the large spin-orbit coupling
STAMENOV, PLAMEN (2013)The Point Contact Andreev Reflection (PCAR) technique has been traditionally and predominantly applied to either the characterisation of superconductors or of spin-polarised metals. The sufficiently large and slowly ...