Emerging electronic devices utilizing spin based effects and phenomena, such as spin transfer tor... more Emerging electronic devices utilizing spin based effects and phenomena, such as spin transfer torque magnetic random access memory (STT-MRAM), have gathered a great spectrum of effort, ranging from basic scientific research to technology development [1][2][3][4]. In this talk, we present a novel all spin logic circuits, referred to as mLogic, based on a four terminal device, referred to as mCell, that utilizes Spin Hall Effect (SHE) along with Dzyaloshinskii-Moriya-Interaction (DMI) at metallic interfaces for its operation [5].
... NiFe/ CoFe free layer to switch, orienting itself either parallel (P) or anti-parallel (AP ..... more ... NiFe/ CoFe free layer to switch, orienting itself either parallel (P) or anti-parallel (AP ... investigated by measuring the current induced magnetic switching properties of the vortex state for CW ... A. Hirohata, M. Hara, T. Kimura, and Y. Otani, Current-induced vortex-vortex switching in a ...
Discrete track recording has emerged as a promising candidate for high storage capacity since it ... more Discrete track recording has emerged as a promising candidate for high storage capacity since it reduces adjacent track erasing (ATE) and alleviates narrow head requirements. In this paper, the writability of discrete lines was studied in discrete track media (DTM) fabricated by e-beam lithography and ion-milling on perpendicular magnetic recording (PMR) media. The writability of discrete lines with finite length
This work demonstrates an anisotropic increase in resistivity with decreasing width in single cry... more This work demonstrates an anisotropic increase in resistivity with decreasing width in single crystal tungsten (W) nanowires having a height of 21 nm. Nanowire-widths were in the range of 15–451 nm, with the anisotropy observed for widths below 50 nm. The longitudinal directions of the nanowires coincided with the <100>, <110> and <111> orientations of the body centered cubic phase of W. The resistivity increase was observed to be minimized for the <111>-oriented single crystal nanowires, exhibiting a factor of two lower increase in resistivity at a width of ~15 nm, relative to the thin film resistivity (i.e., an infinitely wide wire). The observed anisotropy is attributed to crystallographic anisotropy of the Fermi velocity and the resultant anisotropy of the electron mean free path in W and underscores the critical role of crystallographic orientation in nanoscale metallic conduction.
... I would like to take the time to acknowledge those individuals, starting with my advisor Prof... more ... I would like to take the time to acknowledge those individuals, starting with my advisor Prof.Jimmy Zhu. Thank you for entrusting me with such an important research project. ... In particular, I would like to thank Jeff Borandi, Keith Kappel, and Mark Kosarych. ...
Robust magnetic switching and nonvolatility make magnetic random access memory an attractive pros... more Robust magnetic switching and nonvolatility make magnetic random access memory an attractive prospect for future memory designs. However, there has been some concern over whether or not standard fabrication processes can be used to produce annular shaped memory elements. In this paper we present the fabrication and test results of deep submicron annular memory elements defined by electron beam and optical lithographies. The annular memory cells consist of a current perpendicular to plane giant magnetoresistive (CPP GMR) stack containing two ferromagnetic layers with a nonmagnetic interlayer where thin Cu laminations were included in the ferromagnetic layers to enhance the CPP GMR effect.
Annealing effects on the structural and transport properties of sputtered CoFeB∕MgO∕CoFeB magneti... more Annealing effects on the structural and transport properties of sputtered CoFeB∕MgO∕CoFeB magnetic tunnel junctions deposited on SiO2∕Si were investigated. At the as-deposited state, the CoFeB was amorphous at the CoFeB∕MgO interface. High-resolution transmission electron microscope image clearly shows that after annealing at 270°C for 1h, crystallization of amorphous CoFeB (three to four monolayers) with lattice matching to MgO (100) occurred locally at the interface between MgO and CoFeB, producing a magnetoresistance (MR) around 35%–40%. After annealing at 360°C for 40min, the MR increased to 102%. The increase in the MR with annealing is attributed to the complete formation of (100) crystalline structure of CoFeB well lattice matched with the (100)-oriented MgO barrier. The bias voltage dependence of the MR shows a consistent correlation with each CoFeB∕MgO interface.
For discrete track media to become a viable alternative, it is essential to produce accurate serv... more For discrete track media to become a viable alternative, it is essential to produce accurate servo patterns in a cost effective manner. This study presents a spin stand analysis and comparison of position error signals generated from various lithographically defined servo patterns and servo bursts written on continuous regions of the same perpendicular recording media. It is demonstrated that the edge variation on the patterned servo elements is much less than that found on conventional servo bursts. In addition, evidence shows that despite some amplitude loss resulting from the removal of magnetic material, patterned servo bursts produce good quality position error signals when compared to servo bursts written on continuous media.
Emerging electronic devices utilizing spin based effects and phenomena, such as spin transfer tor... more Emerging electronic devices utilizing spin based effects and phenomena, such as spin transfer torque magnetic random access memory (STT-MRAM), have gathered a great spectrum of effort, ranging from basic scientific research to technology development [1][2][3][4]. In this talk, we present a novel all spin logic circuits, referred to as mLogic, based on a four terminal device, referred to as mCell, that utilizes Spin Hall Effect (SHE) along with Dzyaloshinskii-Moriya-Interaction (DMI) at metallic interfaces for its operation [5].
... NiFe/ CoFe free layer to switch, orienting itself either parallel (P) or anti-parallel (AP ..... more ... NiFe/ CoFe free layer to switch, orienting itself either parallel (P) or anti-parallel (AP ... investigated by measuring the current induced magnetic switching properties of the vortex state for CW ... A. Hirohata, M. Hara, T. Kimura, and Y. Otani, Current-induced vortex-vortex switching in a ...
Discrete track recording has emerged as a promising candidate for high storage capacity since it ... more Discrete track recording has emerged as a promising candidate for high storage capacity since it reduces adjacent track erasing (ATE) and alleviates narrow head requirements. In this paper, the writability of discrete lines was studied in discrete track media (DTM) fabricated by e-beam lithography and ion-milling on perpendicular magnetic recording (PMR) media. The writability of discrete lines with finite length
This work demonstrates an anisotropic increase in resistivity with decreasing width in single cry... more This work demonstrates an anisotropic increase in resistivity with decreasing width in single crystal tungsten (W) nanowires having a height of 21 nm. Nanowire-widths were in the range of 15–451 nm, with the anisotropy observed for widths below 50 nm. The longitudinal directions of the nanowires coincided with the <100>, <110> and <111> orientations of the body centered cubic phase of W. The resistivity increase was observed to be minimized for the <111>-oriented single crystal nanowires, exhibiting a factor of two lower increase in resistivity at a width of ~15 nm, relative to the thin film resistivity (i.e., an infinitely wide wire). The observed anisotropy is attributed to crystallographic anisotropy of the Fermi velocity and the resultant anisotropy of the electron mean free path in W and underscores the critical role of crystallographic orientation in nanoscale metallic conduction.
... I would like to take the time to acknowledge those individuals, starting with my advisor Prof... more ... I would like to take the time to acknowledge those individuals, starting with my advisor Prof.Jimmy Zhu. Thank you for entrusting me with such an important research project. ... In particular, I would like to thank Jeff Borandi, Keith Kappel, and Mark Kosarych. ...
Robust magnetic switching and nonvolatility make magnetic random access memory an attractive pros... more Robust magnetic switching and nonvolatility make magnetic random access memory an attractive prospect for future memory designs. However, there has been some concern over whether or not standard fabrication processes can be used to produce annular shaped memory elements. In this paper we present the fabrication and test results of deep submicron annular memory elements defined by electron beam and optical lithographies. The annular memory cells consist of a current perpendicular to plane giant magnetoresistive (CPP GMR) stack containing two ferromagnetic layers with a nonmagnetic interlayer where thin Cu laminations were included in the ferromagnetic layers to enhance the CPP GMR effect.
Annealing effects on the structural and transport properties of sputtered CoFeB∕MgO∕CoFeB magneti... more Annealing effects on the structural and transport properties of sputtered CoFeB∕MgO∕CoFeB magnetic tunnel junctions deposited on SiO2∕Si were investigated. At the as-deposited state, the CoFeB was amorphous at the CoFeB∕MgO interface. High-resolution transmission electron microscope image clearly shows that after annealing at 270°C for 1h, crystallization of amorphous CoFeB (three to four monolayers) with lattice matching to MgO (100) occurred locally at the interface between MgO and CoFeB, producing a magnetoresistance (MR) around 35%–40%. After annealing at 360°C for 40min, the MR increased to 102%. The increase in the MR with annealing is attributed to the complete formation of (100) crystalline structure of CoFeB well lattice matched with the (100)-oriented MgO barrier. The bias voltage dependence of the MR shows a consistent correlation with each CoFeB∕MgO interface.
For discrete track media to become a viable alternative, it is essential to produce accurate serv... more For discrete track media to become a viable alternative, it is essential to produce accurate servo patterns in a cost effective manner. This study presents a spin stand analysis and comparison of position error signals generated from various lithographically defined servo patterns and servo bursts written on continuous regions of the same perpendicular recording media. It is demonstrated that the edge variation on the patterned servo elements is much less than that found on conventional servo bursts. In addition, evidence shows that despite some amplitude loss resulting from the removal of magnetic material, patterned servo bursts produce good quality position error signals when compared to servo bursts written on continuous media.
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