Our results thus paint a richer picture of the currentinduced antiferromagnetic skyrmion motion than discussed recently. The memory device contains two co layers with different perpendicular magnetic anisotropy, separated by a spacer layer of pt. By employing a simple analytical model, we can demonstrate the essential physics that any small current density can drive the dw motion. Currentinduced torques in magnetic materials arne brataas1, andrew d. Currentinduced torque driven ferromagnetic resonance in. Currentinduced domain wall motion with adiabatic and nonadiabatic spin torques in magnetic nanowires z.
Pdf spinorbit torques induced magnetization reversal and domain wall motion devices has. We report measurements of currentinduced torques in heterostructures of permalloy py with tate2, a transitionmetal dichalcogenide tmd material possessing low crystal symmetry, and observe a torque component with dresselhaus symmetry. Our results thus paint a richer picture of the currentinduced antiferromagnetic skyrmion motion. Methods to manipulate the magnetization of ferromagnets by means of local electric fields 1,2,3 or currentinduced spin transfer torque 4,5,6 allow the design of integrated spintronic devices with. Currentinduced spinorbit torques mediate the transfer of angular momentum from the lattice to the spin system, leading to sustained magnetic oscillations or switching of ferromagnetic as well as antiferromagnetic structures. Currentinduced spinorbit torques in ferromagnetic and. In the reciprocal process a changing magnetization orientation produces currents that transport spin angular momentum. Abstract it is shown that the currentinduced torques between a ferromagnetic layer and an antiferromagnetic layer with a compensated interface vanish when the ferromagnet is aligned with an axis of spinrotation symmetry of the antiferromagnet. Macdonalda adepartment of physics, the university of texas at austin, austin, tx 787120264, usa. Magnetic torques and amps law a magnetic field exerts a force on a straight wire carrying current. Pdf spin orbit torques in magnetic materials kiran sethu. Currentinduced switching in the orientation of magnetic moments is observed in cobaltcoppercobalt sandwich structures, for currents flowing perpendicularly through the layers. Currentinduced magnetization switching through spinorbit torques is the fundamental building block of spinorbitronics, which promises highperformance, lowpower memory and logic devices.
As we write from an experimental point of view, we take a heuristic approach to the theory. Currentinduced spinorbit torques mediate the transfer of angular momentum from the lattice to the. Currentinduced torques in ferromagnets at room temperature. Owing to this promising prospect, lots of work have been carried out during the last few decades. This thesis uses ferromagnetic resonance to explore the currentinduced torques cits in two different systems, namely yigheavy metal bilayers and bulk nimnsb, at room temperature. Kent2 and hideo ohno3,4 the magnetization of a magnetic material can be reversed by using electric currents that transport spin angular momentum. Magnetization switching of multistate magnetic structures with. Currentinduced spinorbit torques mediate the transfer of angular momentum from the lattice to the spin system, leading to sustained magnetic oscillations or switching of. This is due to the prospect of devices with reduced size and energy consumption. Us6256223b1 currentinduced magnetic switching device.
Currentinduced torques due to compensated antiferromagnets. Spinorbit coupling in inversionasymmetric magnetic crystals and structures has emerged as a powerful tool to generate complex magnetic textures, interconvert charge and spin under applied current, and control magnetization dynamics. Methods to manipulate the magnetization of ferromagnets by means of local electric fields 1,2,3 or current induced spin transfer torque 4,5,6 allow the design of integrated spintronic devices with. In most cases, generation of spinorbit torques has relied on an external injection of out.
Spinorbit torques in tatbxco100x ferrimagnetic alloy. Currentinduced domain wall motion with adiabatic and. Currentinduced spinorbit torques mediate the transfer of angular momentum from the. The orbital motion of electrons creates tiny atomic current loops, which produce magnetic fields. We analyze the influence of currentinduced torques on the magnetization configuration of a ferromagnet in a circuit containing a compensated. Measurements of the propagation field and the energy barrier for thermally activated dw motion reveal a large currentinduced torque equivalent to an outofplane magnetic field of. This section will outline the phenomenology of domain wall motion in nanowires and the roles played by these torques. It tries to balance out the changing magnetic flux. The spinorbit torques generally arise from spinorbit coupling of heavy metals. Current induced torques in magnetic materials arne brataas1, andrew d. Read currentinduced domain wall motion with adiabatic and nonadiabatic spin torques in magnetic nanowires, the european physical journal b condensed matter and complex systems on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. To measure these spin torques, the researchers used an oscilloscope in a shared facility operated by cornells center for nanoscale systems. Currentdriven spin torque induced by the rashba effect in.
Asymmetric ptcoptstack induced signcontrol of current. Deterministic magnetization switching using lateral spin. Journal of magnetism and magnetic materials vol 320, issue 7. Phenomenology of currentinduced skyrmion motion in.
Tunable chiral spin texture in magnetic domainwalls tunable chiral spin texture in magnetic domainwalls. Currentinduced torques in magnetic metals utrecht university. Roles of joule heating and spinorbit torques in the direct current induced magnetization reversal. Currentinduced torque driven ferromagnetic resonance in magnetic microstructures dong fang this dissertation explores the interaction between the magnetisation and an alternating current in a uniform ferromagnetic system.
A magnetic switching device, includes a first electrode, a second electrode, and a nanoparticle having a magnetic moment and being disposed between the first and second electrodes. We apply a microwave current to the sample while sweeping the external magnetic field, and measure the longitudinal dc voltage. Universal chiraltriggered magnetization switching in confined nanodots universal chiraltriggered magnetization switching in confined nanodots. Diluted magnetic semiconductors ga,mnas and ga,mnas,p have been studied. Magnetic domains in adjacent cobalt layers can be manipulated controllably between stable parallel and antiparallel configurations by applying current pulses of the appropriate sign. The results show that the outofplane component of nonadiabatic stt in fe dw has localized. We investigate currentdriven domain wall dw propagation in magnetic nanowires in the framework of the modified landaulifshitzgilbert equation with both adiabatic and nonadiabatic spin torque ast and nast terms. Currentinduced magnetic domain wall motion cidwm in racetracks has revealed a newly developing magnetic racetrack memory device 1, 2. We present measurements of currentinduced spinorbit torques generated by nbse2, a fully metallic transitionmetal dichalcogenide material, made using the spintorque ferromagnetic resonance stfmr technique with nbse2permalloy bilayers. Currentinduced fourstate magnetization switching by spin. This can provide a very strong torque per unit current, and has been demonstrated to be at least 500 times more efficient than using magnetic fields to write magnetic information, ralph said. By controlling the magnetization orientation through the interplay of magnetocrystalline.
Spinorbit torques in tatb xco 100x ferrimagnetic alloy films with bulk perpendicular magnetic anisotropy kohei ueda, maxwell mann, chifeng pai,a aikjun tan, and geoffrey s. Current induced spintransfer torques stt and spinorbit torques sot enable the electrical switching of magnetic tunnel junctions mtjs in nonvolatile magnetic random access memories. However, even in a heterostructure where a metallic magnet is sandwiched by two. Currentinduced magnetic switching with spinorbit torque in an. Slonczewskis observation that a net spin current flux into a volume of magnetic material implies that a torque acts on the magnetization in that volume is the key idea for most theories of current induced torques cits. Beachb department of materials science and engineering, massachusetts institute.
However, to use 2d vdw magnets for building spintronic nanodevices such as magnetic memories, key challenges remain in terms of effectively switching the magnetization from one state to the. Current induced spinorbit torques mediate the transfer of angular momentum from the lattice to the spin system, leading to sustained magnetic oscillations or switching of ferromagnetic as well as. At least one of the first electrode and the second electrode includes a magnetic material which has a net spin polarization in its conduction band for injecting, into the nanoparticle, an electrical current. This physics video tutorial explains how to calculate the torque on a current loop in a uniform magnetic field as well as the magnetic dipole moment.
We demonstrated currentinduced fourstate magnetization switching in a trilayer system using spinorbit torques. Currentinduced torques in magnetic materials request pdf. We suggest that the dominant mechanism for this dresselhaus component is not a spinorbit torque but rather the oersted field arising from a component of. Currentinduced magnetization switching through spinorbit torques. In deriving we have considered both homogeneous and inhomogeneous currentinduced torques, as well as an external magnetic field applied in the direction. While spin transfer torques stt induced by injecting a spin polarized current into a fmlayer provide a satisfactory solution in many respects1,2.
We report measurements of current induced torques in heterostructures of permalloy py with tate2, a transitionmetal dichalcogenide tmd material possessing low crystal symmetry, and observe a torque component with dresselhaus symmetry. Over the past decade many experiments have confirmed,,, slonczewskis predictions. Wang2 1 institute for theoretical physics, university of regensburg, 93040 regensburg, germany. Physicists measure currentinduced torque in nonvolatile.
Magnetostatics university of colorado colorado springs. Journal of magnetism and magnetic materials 320 2008 011. In this respect, spinorbit torque sot, which originates from the spinorbit interaction, has been widely investigated due to its efficient manipulation of the magnetization using in. Currentdriven domain wall dw motion is investigated in ptcogdox nanostrips with perpendicular magnetic anisotropy. Sot spearheads novel spintronic applications including high. Pdf currentinduced spinorbit torques in ferromagnetic. Journal of magnetism and magnetic materials 320 2008 011 current perspectives currentinduced torques in magnetic metals. Currentinduced spintransfer torques stt and spinorbit torques sot enable the electrical switching of magnetic tunnel junctions mtjs in non. Magnetic torques and amps law rochester institute of. Here, we demonstrate zerofield currentinduced switching of the perpendicular magnetization of a co layer that is indirectly coupled with a. Torque causes an object to spin around a fixed axis. Currentinduced torques with dresselhaus symmetry due to. Currentinduced magnetization switching using an electrically.
An induced voltage generates an induced electric current, which generates the new. Currentinduced spintransfer torques stts have been studied in fe, co and ni domain walls dws by the method based on the firstprinciples noncollinear calculations of scattering wavefunctions expanded in the tightbinding linearized muffintin orbital tblmto basis. Current induced spinorbit torques mediate the transfer of angular momentum from the lattice to the spin system, leading to sustained. Currentinduced torques in magnetic materials nature. In addition to the outofplane oersted torque expected from current flow in the metallic nbse2 layer, we also observe an in. Spinorbit torques in metallic magnetic multilayers. Slonczewskis observation that a net spincurrent flux into a volume of magnetic material implies that a torque acts on the magnetization in that volume is the key idea for most theories of currentinduced torques cits. Inductance of a coil and energy storage l n a l dt di n a l dt d ni a l n dt d n dt di e l p p i p 2. We suggest that the dominant mechanism for this dresselhaus component is not a spinorbit torque but rather the oersted.
The experimental discovery of a rashbatype torque in an fm metal at room temperature opens very promising perspectives in spintronics, namely for the fabrication of magnetic storage and logic gates operating through intrinsic currentinduced so torques. When an external magnetic field is applied to a material, these current loops will tend to align in such a way as to oppose the applied field. Pdf spinorbit coupling in inversionasymmetric magnetic crystals and structures has emerged as a. A current can be induced in a conducting loop if it is exposed to a changing magnetic field. This may be viewed as an atomic version of lenzs law. Current perspectives currentinduced domain wall motion. Induced torques in magnetic materials, cheminform on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Section iii illustrates this debate for the various torques associated with electrical current and their thickness dependencies. Pdf currentinduced spinorbit torques in ferromagnetic and. The effects of electric current have been treated by the addition of two currentinduced torque terms to the llg equation 1115. While the industrial application is mainly focusing on the implementation of currentinduced spin transfer torque stt in magnetic tunnel junctions, a new type of spin torque emerges due to the spinorbit interaction in magnetic multilayers.
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