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We demonstrate experimentally the existence of a continuous phase transition between a normal and a true superconductiug phase (with zero linear resistivity) in epitaxial films of Y-Ba-Cu-0 in strong magnetic fields, H&&H, I. The nonlinear I-V curves show scaling behavior near the transition and the relevant critical exponents are extracted. These exponents are consistent with values expected for freezing into a superconducting vortex-glass phase.

Published by the American Institute of Physics. Related ArticlesComparison of measurements and simulations of series-parallel incommensurate area superconducting quantum interference device arrays fabricated from YBa2Cu3O7−δ ion damage Josephson junctions J. Appl. Phys. 112, 063911 (2012) Nanoparticle magnetization measurements by a high sensitive nano-superconducting quantum interference device Appl. Phys. Lett. 101, 122601 (2012) Superconducting microstrip amplifiers with sub-Kelvin noise temperature near 4GHz Appl. Phys. Lett. 101, 052603 (2012) Note: Low temperature superconductor superconducting quantum interference device system with wide pickup coil for detecting small metallic particles Rev. Sci. Instrum. 83, 076108 (2012) Direct current superconducting quantum interferometers with asymmetric shunt resistors Appl.

Spin-transfer torque magnetic random access memory (STT-MRAM) is one of the most promising emerging non-volatile memory technologies. MRAM has so far been demonstrated with a unique combination of density, speed, and non-volatility in a single chip, however, without the capability to replace any single mainstream memory. In this paper, we demonstrate the basic physics of spin torque switching in 20 nm diameter magnetic tunnel junctions with perpendicular magnetic anisotropy materials. This deep scaling capability clearly indicates the STT MRAM device itself may be suitable for integration at much higher densities than previously proven.

This paper reviews the remarkable developments of the magnetic tunnel junction over the last decade and in particular, work aimed at demonstrating its potential for a dense, fast, and nonvolatile random access memory. The initial focus is on the technological roots of the magnetic tunnel junction, and then on the recent progress made with engineered materials for this device. Following that, we discuss the development of the magnetic random access memory (MRAM) technology, in which the magnetic tunnel junction serves as both the storage device and the storage sensing device. The emphasis is on work at IBM, including demonstrations of basic capabilities of the technology and work on a 16-Mb ''product demonstrator'' design in 180-nm node technology, which was targeted to be a realistic test bed for the MRAM technology. Performance and cost are compared with those of competing technologies. The paper also serves as an introduction to more specialized papers in this issue on MRAM device physics, magnetic tunnel junction materials and device characterization, MRAM processing, and MRAM design.