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Author Lebedev, O.I.; Van Tendeloo, G.; Attfield, J.P.; McLaughlin, A.C.
Title Defect structure of ferromagnetic superconducting RuSr2GdCu2O8 Type A1 Journal article
Year 2006 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 73 Issue 22 Pages (down)
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The structure and defect structure of superconducting ferromagnetic bulk RuSr2GdCu2O8 has been investigated using high-resolution transmission electron microscopy and high-resolution scanning transmission microscopy. Two distinct, but closely related structures, due to ordering of rotated RuO6 octahedra and due to Cu substitution in the Ru-O layer, have been revealed. The structure of Ru1-xSr2GdCu2+xO8-delta can be described as a periodic alteration along the c axis of CuO4 planes and RuO6 octahedra. The unit-cell parameters of this phase are root 2a(p) x root 2a(p) x 2c. The possible influence of this phase and defect structure on the sensitivity of the superconductivity and magnetic properties is discussed. Local defects such as 90 S domain boundaries, (130) antiphase boundaries, and the associated dislocations are analyzed.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000238696300115 Publication Date 2006-06-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 11 Open Access
Notes Iap V-I Approved Most recent IF: 3.836; 2006 IF: 3.107
Call Number UA @ lucian @ c:irua:59707 Serial 619
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Author Nogaret, A.; Peeters, F.M.
Title Electrically induced spin resonance fluorescence: 1: theory Type A1 Journal article
Year 2007 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 76 Issue 7 Pages (down)
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We calculate the fluorescence of electron spins confined to a plane and driven into resonance by a magnetic field gradient and a constant magnetic field applied at right angles to each other. We solve the equation of motion of two-dimensional electrons in the magnetic field gradient to derive the dispersion curve of spin oscillators, the amplitude of electron oscillations, the effective magnetic field sensed by the electron spin, and the rate at which electrons are injected from an electrode into spin oscillators. We then switch on the interaction between the spin magnetic dipole and the electromagnetic field to find the fluorescence power radiated by the individual spin oscillators. The rate of radiative decay is first derived, followed by the probability of sequential photon emission whereby a series of spontaneous decays occurs at random times separated by intervals during which the spin performs Rabi oscillations. The quantum correlations between random radiative decays manifest as bursts of emission at regular intervals along the wire. We integrate all multiphoton processes to obtain an exact analytical expression for the radiated electromagnetic power. The present theory obtains all parameters of the problem including magnetodipole coupling, the particle dwell time in the magnetic field gradient, and the spin polarization of the incoming current. The output power contains a fine structure arising from the anharmonicity of electron oscillations and from nonlinear optical effects which both give satellite emission peaks at odd multiples of the fundamental frequency.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000249155300091 Publication Date 2007-08-09
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 8 Open Access
Notes Approved Most recent IF: 3.836; 2007 IF: 3.172
Call Number UA @ lucian @ c:irua:66117 Serial 897
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Author Nogaret, A.; Lambert, N.J.; Peeters, F.M.
Title Electrically induced spin resonance fluorescence : 2 : fluorescence spectra Type A1 Journal article
Year 2007 Publication Physical Review B Abbreviated Journal Phys Rev B
Volume 76 Issue 7 Pages (down)
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We model the fluorescence spectra of planar spin oscillators to find conditions that maximize spin resonance fluorescence. Spin oscillators perform Rabi oscillations under the effect of a periodic effective magnetic field caused by the winding motion of an electron in a gradient of magnetic field. We show that, despite the weak coupling of the spin magnetic dipole to the vacuum, spin oscillators excited by a direct current output a few nanowatts of microwave power, which is comparable to the best microwave sources. The large quantum efficiency relies on the combination of two effects. On the one hand, the spontaneous emission rate is enhanced by the synchronization of spin oscillators, which interact through the microwave field that they emit. On the other hand, the huge Rabi frequencies experienced by spin oscillators promote spins into upper levels of Zeeman transitions, from which a radiative cascade is triggered. We demonstrate different regimes of fluorescence which correspond to different values of the Rabi period relative to the spontaneous decay time and to the oscillator dwell time in the gradient of magnetic field. We investigate the device parameters which make these regimes experimentally accessible and find conditions that optimize microwave output. We find that microwave emission is centered around the cutoff frequency of spin oscillators. This has the advantage that the peak emission frequency may be tuned from zero continuously up to a few hundred gigahertz using an electrostatic gate. Quite remarkably for a spintronics effect, electrically induced spin resonance fluorescence does not require the injection of a spin polarized current. In fact, we show that microwave spectra are mostly independent of the incoming spin polarization except for magnetic waveguides which are shorter than a certain critical length, which we will specify.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000249155300092 Publication Date 2007-08-09
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 8 Open Access
Notes Approved Most recent IF: 3.836; 2007 IF: 3.172
Call Number UA @ lucian @ c:irua:66118 Serial 898
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Author Pogosov, W.V.; Zhao, H.J.; Misko, V.R.; Peeters, F.M.
Title Kink-antikink vortex transfer in periodic-plus-random pinning potential : theoretical analysis and numerical experiments Type A1 Journal article
Year 2010 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 81 Issue 2 Pages (down)
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The influence of random pinning on the vortex dynamics in a periodic square potential under an external drive is investigated. Using numerical experiments and theoretical approach, we found several dynamical regimes of vortex motion that are different from the ones for a regular pinning potential. Vortex transfer is controlled by kinks and antikinks, which either pre-exist in the system or appear spontaneously in pairs and then propagate. When kinks and antikinks collide, they annihilate. We provide clear physical interpretations of the observed features.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000274002100087 Publication Date 2010-01-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 10 Open Access
Notes ; This work was supported by the “Odysseus” Program of the Flemish government, FWO-Vl, and IAP. W.V.P. acknowledges support from RFBR (Contract No. 09-02-00248). ; Approved Most recent IF: 3.836; 2010 IF: 3.774
Call Number UA @ lucian @ c:irua:81251 Serial 1761
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Author Janssens, K.L.; Partoens, B.; Peeters, F.M.
Title Magneto-excitons in planar type II quantum dots Type A1 Journal article
Year 2001 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 64 Issue 15 Pages (down)
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We study an exciton in a type-II quantum dot, where the electron is confined in the dot, but the hole is located in the barrier material. The exciton properties are studied as a function of a perpendicular magnetic field using a Hartree-Fock mesh calculation. Our model system consists of a planar quantum disk. Angular momentum (l) transitions are predicted with increasing magnetic field. We, also study the transition from a type-I to a type-H quantum dot which is induced by changing the confinement potential of the hole. For sufficiently large magnetic fields a reentrant behavior is found from l(h) = 0 to l(h) not equal 0 and back to l(h) = 0, which results in a transition from type II to type I.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000171694600068 Publication Date 2002-07-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 56 Open Access
Notes Approved Most recent IF: 3.836; 2001 IF: NA
Call Number UA @ lucian @ c:irua:37281 Serial 1900
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