Temperature-induced collapse of spin dimensionality in magnetic metamaterials

Emergent anisotropy in magnetic metamaterials

“…The thin films consisted of Pd (40 nm) -Fe 13 Pd 87 (10 nm) -Pd (2 nm) and were deposited by dc magnetron sputtering on a fused silica substrate in an ultrahigh-vacuum (base pressure below 2 × 10 −7 Pa). A detailed description of the complete process can be found in Skovdal et al [9]. The periodic square arrays of circular islands were fabricated with a fixed edge-to-edge distance of 20 nm and diameters D = 250, 350, and 450 nm.…”

“…The temperature dependence of the magnetization was determined using standard magneto-optical Kerr effect (MOKE) in a longitudinal mode [9]. The incident wavelength of the p-polarized incident laser was set to 659 nm with a spot size of 1 mm 2 , giving the response of approximately million discs.…”

“…In these studies, the magnetic islands -mesospins -have been treated as indivisible building blocks without inner structure, with a classical order-disorder transition of the mesoscopic elements. It is only recently their inner degrees of freedom have been included in the description [9][10][11]. For disk-shaped mesospins, a collection of works addressed dynamics involving bistability of magnetization textures within, depending on geometry and temperature [12,13].…”

“…It was further shown that the size and shape of the mesospins determines also to which extent static internal magnetic textures, such as S-, C-, O-and vortex states, prevail [14][15][16][17]. A more detailed understanding of the role of thermal excitations in the magnetic texture was only recently developed [9,11]. In the light of this, systems allowing for the study of the effect of internal mesospin degrees of freedom on the collective order and thermal dynamics, have been shown to exhibit exotic order-disorder transitions [9,18].…”

“…A more detailed understanding of the role of thermal excitations in the magnetic texture was only recently developed [9,11]. In the light of this, systems allowing for the study of the effect of internal mesospin degrees of freedom on the collective order and thermal dynamics, have been shown to exhibit exotic order-disorder transitions [9,18]. In all of these cases, circular magnetic islands effectively act as XY spins with variable spin lengths.…”