Phase-resolved ferromagnetic resonance using a heterodyne detection method

Yoon, Seungha; Liu, Jason; McMichael, Robert D.

doi:10.1103/physrevb.93.144423

Cited by 20 publications

(19 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As discussed in Ref. [26], to reduce statistical correlations between measurements, N HP maximally separated time slices were selected randomly on each configuration and on each of these time slices, N LP /N HP LP source positions were again selected randomly. The number of sources, N LP and N HP , used are given in Table I.…”

Section: B High Statistics Using the Truncated Solver Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Isovector charges of the nucleon from 2+1+1 -flavor lattice QCD

et al. 2018

View full text Add to dashboard Cite

We present high statistics results for the isovector charges g u−dA , g u−dS and g u−dT of the nucleon. Calculations were carried out on eleven ensembles of gauge configurations generated by the MILC collaboration using highly improved staggered quarks action with 2 þ 1 þ 1 dynamical flavors. These ensembles span four lattice spacings a ≈ 0.06, 0.09, 0.12 and 0.15 fm and light-quark masses corresponding to M π ≈ 135, 225 and 315 MeV. Excited-state contamination in the nucleon three-point correlation functions is controlled by including up to three-states in the spectral decomposition. Remaining systematic uncertainties associated with lattice discretization, lattice volume and light-quark masses are controlled using a simultaneous fit in these three variables. Our final estimates of the isovector charges in the MS scheme at 2 GeV are T with precision low-energy nuclear experiments, and find them comparable to those from the ATLAS and the CMS experiments at the LHC.

show abstract

Section: B High Statistics Using the Truncated Solver Methodsmentioning

confidence: 99%

“…An important conclusion based on all our calculations with O(10 5 ) measurements of nucleon charges and form factors carried out so far (see Refs. [1,3,26,28,29]), is that the difference between the LP and the bias corrected estimates (or the HP) is smaller than the statistical errors.…”

Section: B High Statistics Using the Truncated Solver Methodsmentioning

confidence: 99%

Isovector charges of the nucleon from 2+1+1 -flavor lattice QCD

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The quark propagators were calculated using the Multigrid inverter [17,18] ported in the Chroma software suite [19] with a sloppy stopping criterion. The bias introduced by using a sloppy convergence condition is much smaller than the statistical uncertainty for nucleon observables [12,20] and, therefore, neglected in this study. If necessary, however, it can be easily incorporated by modifying Eq.…”

mentioning

confidence: 99%

Machine learning estimators for lattice QCD observables

2019

View full text Add to dashboard Cite

A novel technique using machine learning (ML) to reduce the computational cost of evaluating lattice quantum chromodynamics (QCD) observables is presented. The ML is trained on a subset of background gauge field configurations, called the labeled set, to predict an observable O from the values of correlated, but less compute-intensive, observables X calculated on the full sample. By using a second subset, also part of the labeled set, we estimate the bias in the result predicted by the trained ML algorithm. The bias-corrected final estimate of the expectation value of O, obtained by running the ML algorithm on the remaining unlabeled set, is improved by combining with the labeled data. A reduction in the computational cost by about 35% is demonstrated for two different lattice QCD calculations using the Boosted decision tree (BDT) regression ML algorithm:(1) prediction of the nucleon three-point correlation functions that yield isovector charges from the two-point correlation functions, and (2) prediction of the phase acquired by the neutron mass when a small Charge-Parity (CP) violating interaction, the quark chromo-electric dipole moment interaction, is added to QCD, again from the two-point correlation functions calculated without CP violation.PACS numbers: 11.15. Ha, 12.38.Gc Simulations of lattice QCD provide values of physical observables from correlation functions calculated as averages over gauge field configurations, which are generated using a Markov Chain Monte Carlo method using the action as the Boltzmann weight [1,2]. Each measurement is computationally expensive and a standard technique to reduce the cost is to replace the 'high precision' (HP) average of an observable O by a 'low precision' (LP) version of it, O LP [3,4], and then perform bias correction (BC), i.e., O = O LP + O − O LP . The method works because the second term can be estimated with sufficient precision from a smaller number of measurements if the covariance between O and O LP is positive and comparable to the variance of O, which is the case if, for example, the fluctuations in either is controlled by effects common to both. One can replace O LP in the above formulation with any quantity whose statistical fluctuations are similar to that of O. Since most underlying gauge dynamics affect a plethora of observables in a similar way, such quantities surely exist; the trick, however, is to find suitable sets of quantities.Machine learning algorithms (ML) build predictive models from data. In contrast to conventional curvefitting techniques, ML does not use "few parameter functional family" of forms for the prediction. Instead, it searches over the entire space of functions approximated using a general form with a large number of free parameters that require a correspondingly large amount of training data to avoid overfitting. ML has been successful for various applications where such data are available, including exotic particle searches [5] and Higgs → τ τ analyses [6] at the Large Hadron Collider. It has recently been applied to ...

show abstract

“…As shown in Ref. [39], the optical signal V O is proportional to the product of the polar magnetization (m y ) and the laser intensity I. The laser intensity is modulated at the microwave frequency ω asĨ = I 0 (1 + e i(ωt+φ L ) )/2 where φ L comes from the phase accumulation from the optical path and is a constant throughout the measurements.…”

Section: O and V Ementioning

confidence: 99%

“…Recently, MOKE-based detection of electrically-induced SOTs have been reported [31][32][33][34], but only with quasi-static magnetization configurations, where the SOT is treated as an "effective field" that tilts the static magnetization of the FM. On the other hand, stroboscopic techniques [35][36][37][38][39], in which both the pump and probe are modulated at the dynamic excitation frequency, offer unique advantages in tracking both the amplitude and the phase information of the magnetization precession, and thus are more suitable in studying SOTdriven spin dynamics.Here, we report a simultaneous electrical and optical measurement of spin-torque ferromagnetic resonance (ST-FMR), with the capability to extract the spin precession phase driven by the SOTs. We show that the spin Hall angle of heavy metals can be directly extracted from the measured optical phase of spin dynamics, in-arXiv:1901.01923v1 [cond-mat.mes-hall]…”

mentioning

confidence: 99%

Simultaneous Optical and Electrical Spin-Torque Magnetometry with Phase-Sensitive Detection of Spin Precession

Sağlam

Zhang

et al. 2019

Phys. Rev. Applied

View full text Add to dashboard Cite

Spin-based coherent information processing and encoding utilize the precession phase of spins in magnetic materials. However, the detection and manipulation of spin precession phases remain a major challenge for advanced spintronic functionalities. By using simultaneous electrical and optical detection, we demonstrate the direct measurement of the precession phase of Permalloy ferromagnetic resonance driven by the spin-orbit torques from adjacent heavy metals. The spin Hall angle of the heavy metals can be independently determined from concurrent electrical and optical signals. The stroboscopic optical detection also allows spatially measuring local spin-torque parameters and the induced ferromagnetic resonance with comprehensive amplitude and phase information. Our study offers a route towards future advanced characterizations of spin-torque oscillators, magnonic circuits, and tunnelling junctions, where measuring the current-induced spin dynamics of individual nanomagnets are required.Magneto-optical Kerr effect (MOKE) provides an alternative approach to "directly" access to the magnetization states. Both in-plane and out-of-plane magnetic moments can be detected [30] by the choice of different Kerr configurations. Recently, MOKE-based detection of electrically-induced SOTs have been reported [31][32][33][34], but only with quasi-static magnetization configurations, where the SOT is treated as an "effective field" that tilts the static magnetization of the FM. On the other hand, stroboscopic techniques [35][36][37][38][39], in which both the pump and probe are modulated at the dynamic excitation frequency, offer unique advantages in tracking both the amplitude and the phase information of the magnetization precession, and thus are more suitable in studying SOTdriven spin dynamics.Here, we report a simultaneous electrical and optical measurement of spin-torque ferromagnetic resonance (ST-FMR), with the capability to extract the spin precession phase driven by the SOTs. We show that the spin Hall angle of heavy metals can be directly extracted from the measured optical phase of spin dynamics, in-arXiv:1901.01923v1 [cond-mat.mes-hall]

show abstract

Phase-resolved ferromagnetic resonance using a heterodyne detection method

Cited by 20 publications

References 40 publications

Isovector charges of the nucleon from 2+1+1 -flavor lattice QCD

Isovector charges of the nucleon from 2+1+1 -flavor lattice QCD

Machine learning estimators for lattice QCD observables

Simultaneous Optical and Electrical Spin-Torque Magnetometry with Phase-Sensitive Detection of Spin Precession

Contact Info

Product

Resources

About