Nanocomposite Co1-xPtx:C films for extremely high-density recording

Abstract

Nanocomposite CoPt:C films were fabricated by sputtering Co, Pt and C onto water‐cooled Si(100) substrates with subsequent annealing. The microstructure and the magnetic properties of these CoPt:C films were investigated as a function of Pt concentration. It was found that the orientations of CoPt grains and the magnetic properties are related strongly to the Pt content. Perpendicular anisotropy was observed in the films with high Pt content. By changing Pt concentrations, films with adjustable coercivity, a grain size less than 10 nm and strong perpendicular magnetic anisotropy were obtained. The crystal lattice structure and the intergranular interactions were proposed to be key factors in the magnetic properties of the CoPt:C films. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Dynamics of Jaynes–Cummings Model in the Absence of Rotating-Wave Approximation

“…In contrast to the approximate solutions in Ref. [15], we have demonstrated an exact time-evolution of a JCM in a wide range of parameters, in the absence of the RWA. We argue that our systematic approach could be applied to various problems regarding JCM without the RWA.…”

“…Our main results include that (i) Wider range of parameters would be available in the calculation, which leads to remarkable discrepancy between RWA and non-RWA, and that (ii) the dynamics of a JCM could be demonstrated more exactly than in Ref. [15]. We have noticed that, in previous papers, [13,14,16] the coherent-state techniques were employed to explore the eigenenergies and the eigenvectors of the JCM systems without the RWA.…”

“…[12] For an ion-trap system, a single ultracold trapped ion experiencing a laser radiation in the treatment of the JCM without the RWA is very different from that with the RWA when the system is moving to the strong excitation regime or going beyond the Lamb-Dicke regime. [13,14] The work in this paper is a generation of a previous solution [15] in which the coherent-state expansion was only made to the third order. Although it is a systematic approach, the calculation made in Ref.…”

“…Although it is a systematic approach, the calculation made in Ref. [15] is only valid in short-time domain and in a narrow range of parameters. We will, in this paper, explore a complete expansion of the coherent-state and thus present an exact dynamics of the JCM in the absence of the RWA.…”