Fabrication of magnetic tunnel junctions connected through a continuous free layer to enable spin logic devices

Magnetic tunnel junctions (MTJs) interconnected via a continuous ferromagnetic free layer were fabricated for Spin Torque Majority Gate (STMG) logic. The MTJs are biased independently and show magnetoelectric response under spin transfer torque. The electrical control of these devices paves the way to future spin logic devices based on domain wall (DW) motion. In particular, it is a significant step toward the realization of a majority gate, even though further downscaling may be required. To our knowledge, this is the first fabrication of a cross-shaped free layer shared by several perpendicular MTJs. The fabrication process can be generalized to any geometry and any number of MTJs. Thus, this framework can be applied to other spin logic concepts based on magnetic interconnect. Moreover, it allows exploration of spin dynamics for logic applications

[1]  C. Ross,et al.  Low Energy Magnetic Domain Wall Logic in Short, Narrow, Ferromagnetic Wires , 2012, IEEE Magnetics Letters.

[2]  Giovanni De Micheli,et al.  Majority-Inverter Graph: A New Paradigm for Logic Optimization , 2016, IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems.

[3]  C. Rettner,et al.  Current-Controlled Magnetic Domain-Wall Nanowire Shift Register , 2008, Science.

[4]  Hiroyuki Ohmori,et al.  Spin Torque Switching of Perpendicularly Magnetized CoFeB-Based Tunnel Junctions With High Thermal Tolerance , 2013, IEEE Transactions on Magnetics.

[5]  Dmitri E. Nikonov,et al.  Automotion of domain walls for spintronic interconnects , 2014 .

[6]  K. Omari,et al.  Chirality-Based Vortex Domain-Wall Logic Gates , 2014 .

[7]  H. Ohno,et al.  Thermal stability of a magnetic domain wall in nanowires , 2015 .

[8]  Berger.  Emission of spin waves by a magnetic multilayer traversed by a current. , 1996, Physical review. B, Condensed matter.

[9]  D Petit,et al.  Magnetic Domain-Wall Logic , 2005, Science.

[10]  K. H. Ploog,et al.  Programmable computing with a single magnetoresistive element , 2003, Nature.

[11]  D. Ralph,et al.  Spin transfer torques , 2007, 0711.4608.

[12]  G. Csaba,et al.  Majority Gate for Nanomagnetic Logic With Perpendicular Magnetic Anisotropy , 2012, IEEE Transactions on Magnetics.

[13]  Wolfgang Porod,et al.  Majority logic gate for 3D magnetic computing. , 2014, Nanotechnology.

[14]  W. Porod,et al.  Shape Engineering for Controlled Switching With Nanomagnet Logic , 2012, IEEE Transactions on Nanotechnology.

[15]  Iuliana Radu,et al.  Operating conditions and stability of spin torque majority gates: Analytical understanding and numerical evidence , 2017 .

[16]  L. Pileggi,et al.  Novel STT-MTJ Device Enabling All-Metallic Logic Circuits , 2012, IEEE Transactions on Magnetics.

[17]  G.E. Moore,et al.  Cramming More Components Onto Integrated Circuits , 1998, Proceedings of the IEEE.

[18]  J. Slonczewski.  Current-driven excitation of magnetic multilayers , 1996 .

[19]  Dmitri E. Nikonov,et al.  (Keynote) Progress, Opportunities and Challenges for Beyond CMOS Information Processing Technologies , 2011 .

[20]  T. Ghani,et al.  Proposal of a Spin Torque Majority Gate Logic , 2010, IEEE Electron Device Letters.

[21]  S. Parkin,et al.  Magnetic Domain-Wall Racetrack Memory , 2008, Science.

[22]  James A. Hutchby,et al.  Limits to binary logic switch scaling - a gedanken model , 2003, Proc. IEEE.

[23]  H. Ohno,et al.  A perpendicular-anisotropy CoFeB-MgO magnetic tunnel junction. , 2010, Nature materials.

[24]  R. Cowburn,et al.  Room temperature magnetic quantum cellular automata , 2000, Science.

[25]  Iuliana Radu,et al.  Toward error-free scaled spin torque majority gates , 2016 .

[26]  H. Ohno,et al.  Process-induced damage and its recovery for a CoFeB–MgO magnetic tunnel junction with perpendicular magnetic easy axis , 2014 .

[27]  Vasile Paraschiv,et al.  STT MRAM patterning challenges , 2013, Advanced Lithography.

[28]  H. Fangohr,et al.  Enhanced spin transfer torque effect for transverse domain walls in cylindrical nanowires , 2011, 1104.3010.

[29]  Seiichiro Higashi,et al.  Solid State Devices and Materials , 2020, Japanese Journal of Applied Physics.

[30]  F. Klose,et al.  Modulating the Magneto-Crystalline Anisotropy and the Exchange Bias Field in CoFe/(Co,Fe)O Bilayers Using Ion-Beam Bombardment and Single Crystalline Substrates , 2012, IEEE Transactions on Magnetics.