Encoding Magnetic States in Monopole‐Like Configurations Using Superconducting Dots

Abstract

A large manifold of nontrivial spin textures, including the stabilization of monopole‐like fields, are generated by using a completely new and versatile approach based on the combination of superconductivity and magnetism. Robust, stable, and easily controllable complex spin structures are encoded, modified, and annihilated in a continuous magnetic thin film by defining a variety of magnetic states in superconducting dots.

Magnetic Recording of Superconducting States

“…While MOI enables detection and analysis of the out-of-plane component of magnetic field, another phenomenon, X-ray magnetic circular dichroism (XMCD) [58], has been recently applied to detect and analyse the in-plane components of the magnetic moment. While the spatial resolution of the MOI technique is ultimately limited by the wavelength of the used visible light, microscopy methods based on XMCD overcome this limitation by replacing visible light with soft X-ray and offer enhanced spatial resolution by utilizing scanning X-ray microscopy [59][60][61][62]. The complementarity of both techniques has indeed been demonstrated in [60] where magnetic X-ray microscopy images based on XMCD and magneto-optical images have revealed the in-plane and out-of-plane field components in YBCO films under similar conditions.…”

“…The XMCD image clearly shows the expected pattern of in-plane components of the magnetic flux density in this state, and hence, demonstrates the efficient recording of the superconducting signal in the Py sensor layer. XMCD has been also utilized in X-ray photoelectron emission microscopy (X-PEEM) to image in-plane magnetic domain configurations in Py induced by underlying YBCO dots [62]. Figure 10a shows SEM images of different samples geometries investigated.…”

Advanced magneto-optical Kerr effect measurements of superconductors at low temperatures

“…1,2 Prominent results can be extracted from magneto-optical Faraday microscopy based on visible light [3][4][5][6][7] or scanning x-ray microscopy (SXM) respectively photoemission electron microscopy (PEEM) based on polarized x-rays featuring higher spatial resolution. [8][9][10] In this paper we show that a magneto-optical Kerr effect (MOKE) set-up in combination with a soft-magnetic sensor layer and an elaborate measurement scheme allows direct access to supercurrents present in thin superconducting films.…”

Observation of the out-of-plane magnetization in a mesoscopic ferromagnetic structure superjacent to a superconductor

“…Recently, low temperature imaging of superconducting flux distribution with sub-50 nm spatial resolution over large areas (>1 mm) has been demonstrated using several element specific x-ray techniques with surface sensitive detection techniques. [9][10][11][12] However, such techniques are challenging due to difficulties in accessing the information from buried interfaces at temperatures below the superconducting critical temperature (T C ). Measurements of the superconducting flux geometry often utilize a magnetic "control layer" 9 deposited on top of a superconductor, where the respective magnetization state reflects the geometry of the flux.…”

“…4(a)] most likely correspond to localized flux patches and have, thus far, not been experimentally observed nor mathematically described within available flux penetration theory. This is because in most experimental and theoretical cases the boundaries of superconducting and ferromagnetic films coincide, 12 therefore offering no way of quantifying edge effects in finite sized magnets.…”