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360° domain walls in planar magnetic nanowires are studied by micromagnetic simulations. It is shown that a nanowire loop with a shape-isotropic wall generator at one end and a shape-anisotropic wall stopper at the other end functions like a data storage stack: 360° domain walls are generated and pushed into stack under rotating field before overflow while popped out and annihilated when field rotating direction is inverted until underflow. The stack capacity is determined by total nanowire loop length. This simple nanowire structure can be integrated into magnetic circuits as an operation unit for 360° domain wall generation and storage. [ABSTRACT FROM AUTHOR]

180° transverse domain walls (TDWs) in planar magnetic nanowires find important applications in advanced logic and memory devices. Controlling DW structure is important because it determines DW behaviors and is used to store digital information. This paper presents, using micromagnetic simulations, simple designs of nanowire unit that enables reliable generation of TDWs and effective control of their structures under rotating magnetic field. It is shown that a series of TDWs can be created, two per loading cycle, and external magnetic field can be programmed to control the TDW structures in terms of their polarity and chirality. These nanowire units and the corresponding magnetic field control schemes can be integrated into magnetic circuits to generate TDWs of controlled structures, facilitating the development of logic and memory devices based on DW functionalities. [ABSTRACT FROM AUTHOR]

To complement recent experimental findings [Vetter et al., APL Mater. 4, 096103 (2016)] on strong exchange coupling effects in Co-Pt nanochessboards featuring a single peak in the first-order reversal curve density plot and associated magnetic hardening as the characteristic structural dimension is reduced below the critical correlation length, the effects of the strong exchange coupling on the underlying magnetic domains and their evolutions are investigated using micromagnetic simulations. The nanochessboard consists of regularly distributed aligned nanorods of a magnetically hard tetragonal L10 phase and a magnetically soft cubic L12 phase, representing a unique type of exchange-coupled magnetic nanocomposites. The simulations reveal detailed magnetic domain processes specific to the nanochessboard structure and uncover an unusual dependence of the coercivity on the length scale, where an expected magnetic hardening is followed by an unexpected magnetic softening with decreasing characteristic dimension. The length scale-dependent exchange coupling effects, effective magnetic anisotropy, and magnetic domain structures and evolution pathways are analyzed to provide insights into the peculiar magnetic behaviors of Co-Pt nanochessboards. [ABSTRACT FROM AUTHOR]