sustainable data storage systems. [4] To further enhance the recording capacity, the magnetic particle size must be reduced. [5,6] However, as magnetic particles become smaller, the thermal stability of the magnetization decreases. In order to maintain the thermal stability, enlargement of the magnetic anisotropy is necessary. Consequently, current magnetic recording heads cannot write against the strong magnetic anisotropy (Figure S1, Supporting Information). This problem is called the "magnetic recording trilemma." [7-11] It is common for magnetic recording media, including hard disk drives and magnetic tapes. To resolve the trilemma problem, several types of recording methods have been proposed such as heat-assisted magnetic recording and microwave-assisted magnetic recording. In basic research, photo-induced phase transitions in magnetic materials are actively studied. [12-23] In the present study, we focus on epsilon iron oxide for two main reasons. It exhibits high-frequency millimeter wave absorption in a wide frequency range of 35-222 GHz due to the zero-field ferromagnetic resonance (Table S1, Supporting Information). Additionally, it can maintain spontaneous magnetization due to ferrimagnetism even with a single nanometer size

The recording performance of a new prototype magnetic tape based on perpendicularly oriented strontium ferrite particles is investigated using a 29 nm wide tunneling magnetoresistive reader. At a linear density of 702 kbpi, a post-detection byte-error rate of 2.8e-2 is demonstrated based on measured recording data and a software read channel. The read channel uses a 64-state implementation of an extended version of a data-dependent noise-predictive maximum-likelihood detection scheme that tracks the first and second order statistics of the data-dependent noise. At the demonstrated post-detection byte-error rate, a post-error-correction-coding byte-error rate of less than 1e-20 can be achieved using an iterative decoding architecture. To facilitate aggressive track-density scaling, we made multiple advances in the area of track following. First, we developed a new timing-based servo pattern and implemented a novel quad channel averaging scheme. Second, we developed a new field programmable gate array prototyping platform to enable the implementation of quad channel averaging. Third, we enhanced our low disturbance tape transport with a pair of 20 mm diameter air bearing tape guides and a prototype track-following actuator. Fourth, we developed a novel low friction tape head and finally, we designed a set of tape speed optimized track-following controllers using the model-based H∞ design framework. Combining these technologies, we achieved a position error signal (PES) characterized by a standard deviation ≤ 3.18 nm over a tape speed range of 1.2 to 4.1 m/s. This magnitude of PES in combination with a 29 nm wide reader enables reliable recording at a track width of 56.2 nm corresponding to a track density of 451.9 ktpi, for an equivalent areal density of 317.3 Gb/in 2 .

There is an everlasting demand for electric motors with smaller size, lighter weight, better efficiency and higher reliability. This paper reports the characteristics of self-lubricating (S-L) magnetic wires specially developed to help meet the demand, and also the result of their application to production of medium size motors.

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