Magnetic Bistability of Co Nanodots

Abstract

Size-dependent magnetic single-domain versus vortex state stability of Co/Ru(0001) nanodots is explored with spin-polarized low-energy electron microscopy, analytical modeling, and micromagnetic simulations. We show that both single-domain and vortex states can be stabilized in a broad region near the phase boundary. The calculated width of the bistability region and temperature dependent heights of the energy barriers between both states agree well with our experimental findings.

Unlocking Bloch-type chirality in ultrathin magnets through uniaxial strain

“…We focus on Fe/Ni bilayer grown on W(110) substrates, where the very large spin Hall angle of tungsten 23 is combined with two-fold symmetry at the (110) interface and perpendicular magnetic anisotropy of the magnetic layer [24][25][26] . Using spin-polarized low-energy electron microscopy (SPLEEM) [27][28][29] , we observe anisotropic chiral DW spin structures with mixed components of chiral Bloch-and chiral Néel-character. We find that, as a function of the relative orientation of the DWs with respect to the [001] substrate surface direction, the Fe/Ni/W(110) system features chiral Néel walls, mixed chiral walls containing both Néel and Bloch components or non-chiral Bloch walls.…”

Chirality control via double vortices in asymmetric Co dots

“…Magnetic vortices in sub-micron sized dots have gained considerable interests in recent years due to their unique reversal mechanisms, fascinating topological properties, and potential applications in information storage, [1][2][3][4][5][6] spin-torque oscillators, 7,8 magnetic memory and logic devices, 9 and targeted cancer-cell destruction strategies. 10 Vortices are one type of topological defects characterized by an in-plane magnetization with a clockwise (CW) or counter-clockwise (CCW) chirality and a central core with an out-of-plane magnetization (up or down polarity).…”

Temperature induced single domain–vortex state transition in sub-100nm Fe nanodots

“…There have been extensive theoretical and experimental studies on SD-VS phase diagrams as a function of nanomagnet dimensions. 6,[8][9][10] Typically, e.g., in isotropic circular dots, the VS evolution from positive saturation starts with an abrupt magnetization drop at a positive nucleation field, followed by a flux closure state with zero remanence and finally the vortex annihilation at a negative field. 6 Observation of the VS at remanence using magnetic microscopy 5 has indeed become a common practice.…”

“…[1][2][3][4] It is known that well above the domain wall width, in micron and submicron sized patterns, magnetization reversal often occurs via a vortex state ͑VS͒. [5][6][7][8] As the nanoelement dimension approaches the exchange length, single domain ͑SD͒ static states are energetically more favorable. There have been extensive theoretical and experimental studies on SD-VS phase diagrams as a function of nanomagnet dimensions.…”