Influence of magnet size on magnetically engineered field-induced superconductivity

W. Gillijns; M. V. Milošević; A. V. Silhanek; V. V. Moshchalkov; F. M. Peeters

doi:10.1103/PhysRevB.76.184516

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Influence of magnet size on magnetically engineered field-induced superconductivity

W. Gillijns, M. V. Milošević, A. V. Silhanek, V. V. Moshchalkov, F. M. Peeters

DOI 10.1103/PhysRevB.76.184516 · Physical Review B

T1

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Abstract

We investigate experimentally and theoretically the superconducting properties of an Al thin film covering a periodic array of Co∕Pt magnetic disks with out-of-plane magnetization for different radii of the magnetic disks and constant period of the magnetic lattice. The presence of the arrays of magnetic dots leads to a quantized displacement of the normal/superconducting phase boundary along the magnetic field axis, with each step corresponding to a flux-quantum per unit cell of the magnetic lattice. We demonstrate that this so-called field-induced superconductivity is strongly dependent not only on the chosen magnetic material and its magnetization M but also on the radius R of the constructed magnetic disks. Since field-induced superconductivity is directly linked to the nucleation of vortex-antivortex (V-AV) pairs, a theoretical M−R equilibrium phase boundary is presented, delimiting regions of different numbers of induced V-AV pairs per magnet. A good qualitative and quantitative agreement is found between theory and experiment.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.35	Pressure not reported	unknown