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. Us6256223b1 currentinduced magnetic switching device. This section will outline the phenomenology of domain wall motion in nanowires and the roles played by these torques. Magnetostatics university of colorado colorado springs. 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. Macdonalda adepartment of physics, the university of texas at austin, austin, tx 787120264, usa. Currentinduced torques due to compensated antiferromagnets. The spinorbit torques generally arise from spinorbit coupling of heavy metals. Over the past decade many experiments have confirmed,,, slonczewskis predictions. Currentinduced spintransfer torques stt and spinorbit torques sot enable the electrical switching of magnetic tunnel junctions mtjs in non.
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. Pdf currentinduced spinorbit torques in ferromagnetic. 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. By employing a simple analytical model, we can demonstrate the essential physics that any small current density can drive the dw motion. In the reciprocal process a changing magnetization orientation produces currents that transport spin angular momentum. Tunable chiral spin texture in magnetic domainwalls tunable chiral spin texture in magnetic domainwalls. Our results thus paint a richer picture of the currentinduced antiferromagnetic skyrmion motion than discussed recently. Spinorbit torques in tatbxco100x ferrimagnetic alloy. Journal of magnetism and magnetic materials 320 2008 011. 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. Asymmetric ptcoptstack induced signcontrol of current. 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. Currentdriven spin torque induced by the rashba effect in.
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. Magnetic torques and amps law a magnetic field exerts a force on a straight wire carrying current. Torque causes an object to spin around a fixed axis. An induced voltage generates an induced electric current, which generates the new. Currentinduced magnetization switching using an electrically. Currentinduced spinorbit torques in ferromagnetic and.
The memory device contains two co layers with different perpendicular magnetic anisotropy, separated by a spacer layer of pt. We demonstrated currentinduced fourstate magnetization switching in a trilayer system using spinorbit torques. 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. Currentinduced torques in ferromagnets at room temperature. 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. Currentinduced domain wall motion with adiabatic and nonadiabatic spin torques in magnetic nanowires z. This is due to the prospect of devices with reduced size and energy consumption. As we write from an experimental point of view, we take a heuristic approach to the theory.
Current induced torques in magnetic materials arne brataas1, andrew d. 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. 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. Journal of magnetism and magnetic materials 320 2008 011 current perspectives currentinduced torques in magnetic metals. Currentinduced torques in magnetic materials arne brataas1, andrew d. Currentinduced torques with dresselhaus symmetry due to. Pdf spinorbit torques induced magnetization reversal and domain wall motion devices has.
Currentinduced spinorbit torques mediate the transfer of angular momentum from the lattice to the. Currentinduced magnetic domain wall motion cidwm in racetracks has revealed a newly developing magnetic racetrack memory device 1, 2. 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. Currentinduced spinorbit torques mediate the transfer of angular momentum from the. Wang2 1 institute for theoretical physics, university of regensburg, 93040 regensburg, germany. Kent2 and hideo ohno3,4 the magnetization of a magnetic material can be reversed by using electric currents that transport spin angular momentum. While spin transfer torques stt induced by injecting a spin polarized current into a fmlayer provide a satisfactory solution in many respects1,2.
Currentdriven domain wall dw motion is investigated in ptcogdox nanostrips with perpendicular magnetic anisotropy. Current perspectives currentinduced domain wall motion. 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. Journal of magnetism and magnetic materials vol 320, issue 7. Section iii illustrates this debate for the various torques associated with electrical current and their thickness dependencies. Owing to this promising prospect, lots of work have been carried out during the last few decades. 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. 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. 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. Magnetization switching of multistate magnetic structures with.
Currentinduced torques in magnetic materials nature. 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. Currentinduced torques in magnetic materials request pdf. Universal chiraltriggered magnetization switching in confined nanodots universal chiraltriggered magnetization switching in confined nanodots. 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. The results show that the outofplane component of nonadiabatic stt in fe dw has localized.
Currentinduced torque driven ferromagnetic resonance in. It tries to balance out the changing magnetic flux. 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. However, even in a heterostructure where a metallic magnet is sandwiched by two. By controlling the magnetization orientation through the interplay of magnetocrystalline. Phenomenology of currentinduced skyrmion motion in. In most cases, generation of spinorbit torques has relied on an external injection of out. The orbital motion of electrons creates tiny atomic current loops, which produce magnetic fields. Current induced spinorbit torques mediate the transfer of angular momentum from the lattice to the spin system, leading to sustained. In deriving we have considered both homogeneous and inhomogeneous currentinduced torques, as well as an external magnetic field applied in the direction. Currentinduced magnetization switching through spinorbit torques. 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. 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.
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. Currentinduced magnetization switching through spinorbit torques is the fundamental building block of spinorbitronics, which promises highperformance, lowpower memory and logic devices. 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. 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. Current induced spintransfer torques stt and spinorbit torques sot enable the electrical switching of magnetic tunnel junctions mtjs in nonvolatile magnetic random access memories. Currentinduced magnetic switching with spinorbit torque in an. Beachb department of materials science and engineering, massachusetts institute. Diluted magnetic semiconductors ga,mnas and ga,mnas,p have been studied. 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. Sot spearheads novel spintronic applications including high. Roles of joule heating and spinorbit torques in the direct current induced magnetization reversal.
We analyze the influence of currentinduced torques on the magnetization configuration of a ferromagnet in a circuit containing a compensated. 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. 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. Pdf spin orbit torques in magnetic materials kiran sethu. In addition to the outofplane oersted torque expected from current flow in the metallic nbse2 layer, we also observe an in. 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. 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. To measure these spin torques, the researchers used an oscilloscope in a shared facility operated by cornells center for nanoscale systems. Currentinduced torques in magnetic metals utrecht university. Magnetic torques and amps law rochester institute of. We suggest that the dominant mechanism for this dresselhaus component is not a spinorbit torque but rather the oersted.
Currentinduced switching in the orientation of magnetic moments is observed in cobaltcoppercobalt sandwich structures, for currents flowing perpendicularly through the layers. 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. Magnetic domains in adjacent cobalt layers can be manipulated controllably between stable parallel and antiparallel configurations by applying current pulses of the appropriate sign. Here, we demonstrate zerofield currentinduced switching of the perpendicular magnetization of a co layer that is indirectly coupled with a. Deterministic magnetization switching using lateral spin. Our results thus paint a richer picture of the currentinduced antiferromagnetic skyrmion motion.
Currentinduced spinorbit torques mediate the transfer of angular momentum from the lattice to the spin system, leading to sustained magnetic oscillations or switching of. Physicists measure currentinduced torque in nonvolatile. Currentinduced fourstate magnetization switching by spin. Pdf currentinduced spinorbit torques in ferromagnetic and. Currentinduced domain wall motion with adiabatic and. 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. The effects of electric current have been treated by the addition of two currentinduced torque terms to the llg equation 1115. This may be viewed as an atomic version of lenzs law.
853 1236 662 1548 955 359 585 377 304 211 854 1174 1363 789 244 431 589 1535 719 1536 930 798 53 561 994 360 567 856 1316 979 852 1306 1263