Gyrator Based on Magneto-elastic Coupling at a Ferromagnetic/Piezoelectric Interface

Bhuktare, Swapnil; Bose, Arnab; Singh, Harbans; Tulapurkar, Ashwin

doi:10.1038/s41598-017-00960-9

Cited by 26 publications

(22 citation statements)

References 21 publications

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“…3(c). It follows a sin 2 (θ)cos(θ) dependence and shows a four fold symmetry, a peculiar characteristic of the magneto elastic coupling [15,22]. The peak position of |S 12 | as a function of θ is shown in Fig.…”

Section: Fig2 St-fmr Study: (A) the DC Voltage Spectrum As A Functiomentioning

confidence: 93%

“…It should be noted that the transmission of signal between the two ports involves a large delay (distance between the ports/saw velocity) which affects the phase of the S 12 and S 21 signals. Thus the shape of the real and imaginary parts can be a combination of peak and dispersion shapes depending on the delay [22]. From Fig 3(a) and 3(b), we see that S 12 and S 21 have 180 degree phase shift, however the generalized reciprocity relation S 12 (B)=S 21 (-B) is obeyed.…”

Section: Fig2 St-fmr Study: (A) the DC Voltage Spectrum As A Functiomentioning

confidence: 94%

“…Ni pumps back spin current into Pt which is converted into voltage by ISHE. This gives rise to the reflected voltage signal which is measured as S 22 . The S 22 signal of device 3 originates as follows: The magnetization of Ni is excited by Oersted field generated by current flowing in Au (Ampere's law).…”

Section: ) S-parameters Of Device 2 Andmentioning

confidence: 99%

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Direct observation of the reciprocity between spin current and phonon interconversion

Bhuktare

Shukla

Singh

et al. 2019

Applied Physics Letters

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Spin current has emerged as a leading candidate for manipulation of spins in a nanomagnet. We here experimentally show another utility of spin current viz. it can be used for generation of phonons. Within the same experimental setup, we also demonstrate the inverse effect of generation of spin current by phonons. To demonstrate them, we measured the scattering-matrix of a two-port device with interdigital transducers as one port and array of Ni/Pt lines as second port on piezoelectric substrate. The off-diagonal elements which correspond to transmission between the ports, were found to have 180 o relative phase shift. The transmission of electrical signal from port 2 to 1 corresponds to generation of phonons from spin-current, while transmission from port 1 to 2 corresponds to the inverse effect. These results could be useful for designing spin-current based gyrators.Spintronics exploits the spin degree of freedom of an electron for various new functionalities [1]. The coupling of spins to heat currents (spin caloritronics) [2-9] orbital momentum (spin orbitronics) [10][11][12][13] or the mechanical degrees of freedom (spin mechanics) [14][15][16][17][18][19][20][21][22] has generated a lot of interest due to the novel physics involved and potential new applications of spin current. This coupling has enabled observation of various new phenomena such as spin Seebeck effect [3][4][5][6], acoustically driven resonance [15][16][17] etc. Spin seebeck effect refers to the generation of spin current over a macroscopic scale by temperature gradient, whereas in acoustically driven resonance, mechanical motion is used to excite spin dynamics. We here demonstrate that spin current can be used to excite phonons, which can travel macroscopic distances of the order of millimeter. Our experiment utilizes a piezoelectric LiNbO 3 substrate over which we fabricate a periodic array of Ni/Pt lines. We observed that when current is passed through Ni/Pt lines, phonons in the form of surface acoustic waves (SAW) are emitted, which can be detected by using interdigital transducers (IDT). This phonon emission involves many spin based phenomena: i) Conversion of charge current into spin current by spin-Hall effect (SHE) in Pt ii) Excitation of magnons in Ni by spin current via spin-transfer torque (STT) effect iii) emission of phonons by magnons via magneto-elastic coupling. Our setup also allows us to measure the inverse effect i.e. generation of spin current by phonons [19]. The inverse effect proceeds via inverse of the above three steps: i) generation of magnons by phonons via inverse magneto-elastic coupling ii) injection of spin current in Pt via. inverse STT effect or spin pumping iii) Conversion of spin current into charge current by inverse spin-Hall effect (ISHE) in Pt.Our experiments show that the transmission of electrical signal from IDTs to Ni/Pt lines (S 21 ) and transmission from Ni/Pt lines to IDTs (S 12 ) have opposite sign i.e. S 12 =-S 21 i.e. the Corresponding Author* Email: ashwin@ee.iitb.ac.in Author ContributionsTh...

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Section: Fig2 St-fmr Study: (A) the DC Voltage Spectrum As A Functiomentioning

confidence: 93%

Section: Fig2 St-fmr Study: (A) the DC Voltage Spectrum As A Functiomentioning

confidence: 94%

See 1 more Smart Citation

Direct observation of the reciprocity between spin current and phonon interconversion

Bhuktare

Shukla

Singh

et al. 2019

Applied Physics Letters

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“…Another approach to produce non-reciprocal behavior is to apply an external symmetry breaking bias field. External magnetic field bias is commonly used [11][12][13][14] although similar symmetry breaking has been demonstrated in a linear acoustic device with a circulating fluid that creates an angular-momentum bias [15] and by using magneto-elastic coupling to create a gyrator [16]. Wang et al [17] demonstrated breaking time reversal symmetry using gyroscopic inertial effects that creates an apparent external force.…”

Section: Introductionmentioning

confidence: 99%

Nonreciprocal wave propagation and parametric amplification of bulk elastic waves in nonlinear anisotropic materials

et al. 2020

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Parametric amplification of an elastic wave and a framework for using elastic waves that could enable a new generation of high performance, low noise acoustic amplifiers, mixers and circulators are presented. Using a novel approach with nonlinear materials produces highly desirable non-reciprocal characteristics. Parametric amplification of a weak elastic signal wave is achieved by an elastic pump wave of higher intensity. By careful selection of material orientation together with precise excitation of signal and pump waves, 'up frequency conversion' is suppressed and selective amplification of the elastic signal wave occurs at its original frequency. In addition, a general mathematical framework is developed and used for analytical studies of coupled wave equations in nonlinear anisotropic materials. The results obtained from the analytical studies are verified using a finite element implementation.

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“…Here, we show that effective magnetic damping can be controlled by SNT while creating thermal gradient in Pt/Ni81Fe19 bilayer. This can open a new avenue to manipulate spins in magnetic nanostructures for technological applications 27,28,29 .…”

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confidence: 99%

Control of magnetization dynamics by spin-Nernst torque

et al. 2018

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Relativistic interaction between electron's spin and orbital angular momentum has provided efficient mechanism to control magnetization of nano-magnets. Extensive research has been done to understand and improve spin-orbit interaction driven torques generated by non-magnets while applying electric current. In this work, we show that heat current in non-magnet can also couple to its spin-orbit interaction to produce torque on adjacent ferromagnet. Hence, this work provides a platform to study spin-orbito-caloritronic effects in heavy metal/ferromagnet bi-layers.Since last few years considerable attention has been drawn to control the magnetization dynamics by pure spin current generated by spin Hall effect (SHE) 1,2,3,4 and interfacial magnetic fields 5,6 by Rashba effect. SHE and Rashba effects are relativistic phenomena which couple electron's spin and orbital motion and can be used to exert spin-orbit torques 7 , 8 . On the other hand, thermal gradient in ferromagnet can also create pure spin current 9,10,11,12,13 which can further produce thermal spin torques 14,15,16,17,18 and domain wall motion 19,20 . Conversion of heat current into spin current in a non-magnet has been shown recently via the spin Nernst effect (SNE) 21,22,23,24 . But an important question remains unanswered whether thermal gradient in non-magnet can generate spin toque owing to its spin-orbit coupling, which in turn could be used for manipulating magnetization. In this letter we demonstrate that, interplay of heat current and spin-orbit coupling in non-magnetic Platinum (Pt) can generate thermally driven spin-orbit torque (equivalent to spin Nernst torque (SNT)). SNT has been predicted recently 25,26 but it is lacking the experimental evidence. Here, we show that effective magnetic damping can be controlled by SNT while creating thermal gradient in Pt/Ni81Fe19 bilayer. This can open a new avenue to manipulate spins in magnetic nanostructures for technological applications 27,28,29 .

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Gyrator Based on Magneto-elastic Coupling at a Ferromagnetic/Piezoelectric Interface

Cited by 26 publications

References 21 publications

Direct observation of the reciprocity between spin current and phonon interconversion

Direct observation of the reciprocity between spin current and phonon interconversion

Nonreciprocal wave propagation and parametric amplification of bulk elastic waves in nonlinear anisotropic materials

Control of magnetization dynamics by spin-Nernst torque

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