80% tunneling magnetoresistance at room temperature for thin Al–O barrier magnetic tunnel junction with CoFeB as free and reference layers

Abstract

Magnetic tunnel junctions (MTJs) with structures of Ta(5)∕Cu(10)∕Ta(5)∕Ir21Mn79(10)∕Co75Fe25(2)∕Ru(0.75)∕Co40Fe40B20(3)∕Al(0.6)–O∕Co40Fe40B20(2.5)∕Ta(3)∕Ru(7) (units in nanometers) were deposited via ultrahigh vacuum magnetron sputtering (ULVAC). Microscale ring-type magnetic tunnel junctions (RMTJs) with an outer radius of 2μm and an inner radius of 1μm were patterned using standard UV lithography combined with ion milling. Both reference and free layers were Co40Fe40B20 and a very thin Al–O (0.6nm) barrier layer was used. Tunneling magnetoresistances (TMRs) of up to 81% at room temperature and 107% at 4.2K were observed. These RMTJs with high TMR and low coercivity, of about 26Oe, combined with the ring-type geometry, which greatly reduces stray magnetic field, are ideal for certain magnetic field sensor applications.

Annealing effect on tunneling magnetoresistance in MgO-based magnetic tunnel junctions with FeMn exchange-bias layer

“…When the reverse applied field exceeds the exchange bias H ex (∼ 6 mT), the SAF stack reverses, giving the low resistance state. The switching field of the free CoFeB layer is H c (∼ 1.1 mT), which is similar to that reported by Wei et al [13]. The resistance of the stack is high or low, according to the relative alignments of the two CoFeB layers, as indicated in Fig.…”

“…5). Besides, due to the elemental diffusion at the CoFeB/MgO interfaces at high T a , the highest TMR value for these MgO-based FeMn-MTJs is even lower than that for the AlO x -based MTJs [13]. Hence almost no coherent tunneling process takes place for these FeMn-MTJs.…”

Magnetoresistance Effect in NiFe/BP/NiFe Vertical Spin Valve Devices

“…Recently, the 2D nanomaterials have also been demonstrated to have potential for application in the field of spintronics [4][5][6][7][8][9][10][11]. The 2D materials have been largely researched as nonmagnetic interlayer of spin valve, which is similar to traditional magnetic tunneling junctions consisting of two ferromagnetic (FM) layers separated by a nonmagnetic insulating spacer, usually Al 2 O 3 and MgO, and the resistance depends on the magnetization orientation of two ferromagnetic electrodes [12,13]. The first experimental work for realization of spintransport phenomenon is reported by Tombros et al in graphene-based planar spin valve structure [4].…”

Magnetic logic based on diode-assisted magnetoresistance

“…6c. 30 GMR, 31 AlO x -TMR, 32 MgO-TMR, 33 SVT, 34 MTT, 35 Organic MR, 36 InSb MR, 22 Si MR 16 and our new MR. Our MR device could be further extended to all four basic Boolean logic operations including AND, OR, NAND and NOR. For the logic operations of AND, OR, NAND and NOR, two PMA multilayer films as two magnetic logic input bits were required.…”