Spin Precession Frequency Research Articles

Plausibility of Capture into High-obliquity States for Exoplanets in the M Dwarf Habitable Zone

For temperate exoplanets orbiting M-dwarf hosts, the proximity of the habitable zone to the star necessitates careful consideration of tidal effects. Spin synchronization of the planetary orbital period and rotation period, tidal locking, and the subsequent impact on surface conditions frames common assumptions about M-dwarf planets. We investigate the plausibility of capture into Cassini State 2 (CS2) for a known sample of 280 multiplanet systems orbiting M-dwarf hosts. This resonance of the spin precession and orbital precession frequencies can excite planets into stable nonzero rotational obliquities, breaking tidal locking and inducing a version of “day” and “night.” Considering each planetary pair and estimating the spin and orbital precession frequencies, we find that 75% of detected planets orbiting M dwarfs may be plausibly excited to a high obliquity and maintain it through subsequent tidal dissipation over long timescales. We also investigate two possible mechanisms for capture into CS2: quantifying the orbital migration or primordial obliquity necessary for CS2. We find orbital migrations by a factor of ≲2 and an isotropic initial spin distribution can produce high-obliquity planets, aligning with similar findings for planets orbiting close-in to FGK dwarfs. Many of the planets in our sample reside in both CS2 and within their stellar habitable zone. Over half of the planets with T eq < 400 K around host stars with T eff < 3000 K could possess nonzero obliquity due to residence in CS2. This overlap renders the potential capture into Cassini States extremely relevant to understanding the galaxy’s most common temperate planets.

Kinetics of optical phonons and DP depolarization of spins in drift transport: Hot carrier spin effect in semiconductors

&lt;p&gt;Spin-&lt;strong&gt;c&lt;/strong&gt;onserving transport of carriers is an essential requirement for the practical semiconductor-based spintronic devices. Kinetics of optical phonons and Dyakonov-Perel (DP) depolarization of spins in drift transport in semiconductor gallium arsenide (GaAs) is theoretically investigated&lt;strong&gt;. &lt;/strong&gt;We consider electrons in &lt;em&gt;n&lt;/em&gt;-type bulk GaAs subjected to a strong electric field, where the electron distribution is assumed to be drifted Maxwellian. The momentum drift of this distribution results in the enhanced drift velocity, and electrons with the corresponding energy emit optical hot phonons in the drifting process. The hot phonons are incorporated via the longitudinal polar optical phonon (POP) mechanism in the momentum relaxation. It is found that a finite phonon lifetime can reduce the momentum relaxation rate, which results in a delay in the runaway to higher fields, where the effect increases with the electron density. The electron spin is found to relax with the DP relaxation frequencies, and the DP spin lifetimes are found to decrease with increasing the drift field. However, a high field completely depolarizes the electron spin due to an increase of the DP spin precession frequency of the hot electrons in the POP scattering process. It is also found that the DP spin precession frequency decreases with decreasing electron temperature or increasing electron density in the moderate range. However, the findings resulting from this investigation demonstrate the hot carrier effect in the spin transport in semiconductors. The results are discussed in comparison with those obtained in earlier experimental and theoretical studies with different approaches.&lt;/p&gt;

Sub-THz High Spin Precession Frequency in van der Waals Ferromagnet Fe3GaTe2.

The 2D magnet Fe3GaTe2 has received considerable attention for its high Curie temperature (TC), robust intrinsic ferromagnetism, and significant perpendicular magnetic anisotropy (PMA). In this study, the dynamic magnetic properties of Fe3GaTe2 are systematically investigated using an all-optical pump-probe technique. We find that the spin precession frequency (f) is as high as 351.2 GHz at T = 10 K under a field of H = 70 kOe. However, it decreases to 242.8 GHz at 300 K, mainly due to the reduced effective PMA field (Hkeff). The Gilbert damping factor (α) is modest, which increases from 0.039 (10 K) to 0.075 (300 K) owing to the enhanced scattering rate. Interestingly, when Fe3GaTe2 is coupled with 2 nm of Co, the Hkeff, f, and α just decrease slightly, highlighting the dominant influence of Fe3GaTe2. These findings substantially deepen our understanding of Fe3GaTe2, promoting the development of spintronic devices based on advanced 2D magnetic materials.

Detailed report on the measurement of the positive muon anomalous magnetic moment to 0.20 ppm

We present details on a new measurement of the muon magnetic anomaly, aμ=(gμ−2)/2. The result is based on positive muon data taken at Fermilab’s Muon Campus during the 2019 and 2020 accelerator runs. The measurement uses 3.1 GeV/c polarized muons stored in a 7.1-m-radius storage ring with a 1.45 T uniform magnetic field. The value of aμ is determined from the measured difference between the muon spin precession frequency and its cyclotron frequency. This difference is normalized to the strength of the magnetic field, measured using nuclear magnetic resonance. The ratio is then corrected for small contributions from beam motion, beam dispersion, and transient magnetic fields. We measure aμ=116592057(25)×10−11 (0.21 ppm). This is the world’s most precise measurement of this quantity and represents a factor of 2.2 improvement over our previous result based on the 2018 dataset. In combination, the two datasets yield aμ(FNAL)=116592055(24)×10−11 (0.20 ppm). Combining this with the measurements from Brookhaven National Laboratory for both positive and negative muons, the new world average is aμ(exp)=116592059(22)×10−11 (0.19 ppm). Published by the American Physical Society 2024

NICA Facilities for the Search for EDM Light Nuclei

To search for proton Electric Dipole Moments (EDM) using proton storage ring with purely electrostatic elements, the concept of frozen spin method has been proposed by Brookhaven National Laboratory. This method is based on two facts: in the equation of spin precession, the magnetic field dependence is entirely eliminated, and at the ‘‘magic’’ energy, the spin precession frequency coincides with the precession frequency of the particle momentum. In case of deuteron, we have to use the electrical and magnetic field simultaneously, keeping the frozen spin direction along the momentum as in the pure electrostatic ring. Later, Yu. Senichev proposed the concept of quasi-frozen spin, in which the spin oscillates around the direction of the pulse within half the value of the advanced phase of rotation in magnetic arcs, each time returning back in deflectors with an electrostatic field. Due to the low value of the anomalous magnetic moment of deuteron, an effective contribution to the expected EDM effect is reduced only by a few percent compared with frozen spin method. In this work, we consider the adapted structure of the NICA and Nuclotron synchrotrons, in which the ‘‘quasi-frozen spin’’ option can be implemented. The advantage of the ‘‘quasi-frozen spin’’ concept is the possibility of using synchrotrons already existing in the world that are not focused on studying EDM, which makes this method the only one possible for the accelerators of the NICA complex.

The Xe isotope nuclear resonance frequency shift of NMR angular velocity sensors due to transverse gradient magnetic fields

The nuclear magnetic resonance (NMR) angular velocity sensor detects angular velocity by measuring the shift in the nuclear spin precession frequency, which is of fundamental interest. Recent studies have revealed the parameter dependency of nuclei frequency shifts induced by non-uniformly distributed polarized pump beams, temperature, and magnetic field properties. In this study, we investigated the effect of the linear transverse gradient magnetic field on the frequency ratio shift of the Xe isotope nuclear resonance frequency in the NMR sensors. A theoretical analysis method was proposed based on the Fermi contact interaction in atomic polarization and the spin-diffusion relaxation of 129Xe and 131Xe nuclei. The frequency ratio shift of the Xe isotope under different x-axis gradient magnetic fields was measured experimentally. Furthermore, we eliminated the equivalent residual magnetic field through a feedback system and compensated for the original gradient magnetic field in the system, which contributed to accurately revealing the frequency shift induced by the magnetic field gradient. The results indicate that the frequency ratio shift of the Xe isotope is proportional to the strength of the second-order linear transverse gradient magnetic field. This study provides a reference for the analysis and evaluation of the presence of the gradient magnetic field in the NMR angular velocity sensor.

Formula E=mc2 as a Property of a Spin Vortex in the Physical Vacuum. The Force of Inertia

The aim of this work is to show that in well-known expression Е=mc2 symbols m and E denote respectively the mass and energy of spin vortex (of photon or virtual photon) in the physical vacuum, and the energy may be written by expression: E = ℏω, where ℏ is the Planck constant, ω is the precession frequency of spin in the spin vortex. For this purpose, the properties of spin vortex (spin, mass, electric dipole moment) are analyzed. Based on the conducted investigation, the expression for the force of inertia of a moving body is deduced, and it is proven that experimentally observed change in the weight of body during its rotation can be accomplished by the force of inertia. It is shown that the mass connected with the motion of quantum object is formed in a virtual photon like the rest mass of quantum object is formed in a photon, and this formation is carried out by pseudomagnetic interaction

Search for Spin-Dependent Gravitational Interactions at Earth Range.

Among the four fundamental forces, only gravity does not couple to particle spins according to the general theory of relativity. We test this principle by searching for an anomalous scalar coupling between the neutron spin and the Earth's gravity on the ground. We develop an atomic gas comagnetometer to measure the ratio of nuclear spin-precession frequencies between ^{129}Xe and ^{131}Xe, and search for a change of this ratio to the precision of 10^{-9} as the sensor is flipped in Earth's gravitational field. The null results of this search set an upper limit on the coupling energy between the neutron spin and the gravity on the ground at 5.3×10^{-22} eV (95% confidence level), resulting in a 17-fold improvement over the previous limit. The results can also be used to constrain several other anomalous interactions. In particular, the limit on the coupling strength of axion-mediated monopole-dipole interactions at the range of Earth's radius is improved by a factor of 17.

Concomitant modulation of interlayer exchange coupling and Gilbert damping in Fe/CoO with spin conductor Ag layer at interface

We report on the modulation of interlayer exchange coupling (IEC) between the ferromagnet (FM) Fe and insulating antiferromagnet (AFM) CoO and its impact on the Gilbert damping by a time-resolved magneto-optical Kerr effect technique. By inserting a wedge spin conductor Ag layer at the interface of Fe/CoO, it is revealed that both uniform spin precession frequency and Gilbert damping constant of Fe film decrease with increasing Ag thickness up to ∼2 nm, and above that with eliminated IEC, these two parameters reach the intrinsic values of the Fe film. The precession frequency and damping also show similar variation tendency with temperature for attenuated IEC. These results prove that the exchange coupling at the FM–AFM interface plays an essential role for the spin angular momentum transfer to the insulating AFM layer, and the spin pumping is insignificant even for the very thin spin conductor layer. Our findings may have general insights into the role of the FM/AFM interface in the magnetization dynamics and spin angular momentum transfer for future spintronic applications.

Precession and Lense-Thirring effect of hairy Kerr spacetimes

We investigate the frame-dragging effect of the hairy Kerr spacetimes on the spin of a test gyro and accretion disk. First, we analyze Lense-Thirring (LT) precession frequency, geodetic precession frequency, and the general spin precession frequency of a test gyro attached to a stationary observer in the spacetime. We find that the black hole hair suppresses those precession frequencies in comparison with that which occurs in Kerr spacetime in general relativity. Moreover, using those frequencies as a probe, we differentiate the hairy Kerr black hole (BH) from naked singularity (NS). Specifically, as the observer approaches the central source along any direction, the frequencies grow sharply for the hairy Kerr BH, while for the hairy NS they are finite except at the ring singularity. Then, we investigate the quasiperiodic oscillations (QPOs) phenomena as the accretion disk approaches the hairy Kerr BH or NS. To this end, we analyze the bound circular orbits and their perturbations. We find that as the orbits approach the corresponding innermost stable circular orbit (ISCO), both LT precession frequency and periastron precession frequency behave differently in the hairy Kerr BH and NS. Additionally, the hairy parameters have significant effects on the two frequencies. We expect that our theoretical studies could shed light on astrophysical observations in distinguishing hairy theories from Einstein's gravity, and also in distinguishing BH from NS in spacetime with hair.

Performance Enhancement of a Spin-Wave-Based Reservoir Computing System Utilizing Different Physical Conditions

We numerically study how to enhance reservoir computing performance by thoroughly extracting the spin-wave device potential for higher-dimensional information generation. The reservoir device has a 1-input exciter and 120-output detectors on the top of a continuous magnetic garnet film for spin-wave transmission. For various nonlinear and fading-memory dynamic phenomena distributing in the film space, small in-plane magnetic fields are used to prepare stripe domain structures and various damping constants at the film sides and bottom are explored. The ferromagnetic resonant frequency and relaxation time of spin precession clearly characterizes the change in spin dynamics with the magnetic field and damping constant. The common input signal for reservoir computing is a 1-GHz cosine wave with random 6-valued amplitude modulation. A basic 120-dimensional reservoir output vector is obtained from time-series signals at the 120-output detectors under each of three magnetic field conditions. Then, 240- and 360-dimensional reservoir output vectors are also constructed by concatenating two and three basic ones, respectively. In nonlinear autoregressive moving average (NARMA) prediction tasks, the computational performance is enhanced as the dimension of the reservoir output vector becomes higher and a significantly low prediction error is achieved for the tenth-order NARMA task using the 360-dimensional vector and optimum damping constant. The results are clear evidence that the collection of diverse output signals efficiently increases the dimensionality of the integrated reservoir state vector (i.e. reservoir-state richness) and thereby contributes to high computational performance. This paper demonstrates that performance enhancement through various configuration settings is a practical approach for on-chip reservoir computing devices with small numbers of real output nodes.

Stable Atomic Magnetometer in Parity-Time Symmetry Broken Phase.

Random motion of spins is usually detrimental in magnetic resonance experiments. The spin diffusion in nonuniform magnetic fields causes broadening of the resonance and limits the sensitivity and the spectral resolution in applications like magnetic resonance spectroscopy. Here, by observation of the parity-time (PT) phase transition of diffusive spins in gradient magnetic fields, we show that the spatial degrees of freedom of atoms could become a resource, rather than harmful, for high-precision measurement of weak signals. In the normal phase with zero or low gradient fields, the diffusion results in dissipation of spin precession. However, by increasing the field gradient, the spin system undergoes a PT transition, and enters the PT symmetry broken phase. In this novel phase, the spin precession frequency splits due to spatial localization of the eigenmodes. We demonstrate that, using these spatial-motion-induced split frequencies, the spin system can serve as a stable magnetometer, whose output is insensitive to the inevitable long-term drift of control parameters. This opens a door to detect extremely weak signals in imperfectly controlled environments.

Effects of spin-exchange collisions on the fluctuation spectra of hot alkali-metal vapors

We present a first-principles analysis of the noise spectra of alkali-metal-metal vapors in and out of the spin-exchange-relaxation-free (SERF) regime, and we predict non-intuitive features with a potential to further improve the sensitivity of SERF media, and which must be taken into account in their use in quantum optical applications. Studying the process of spin-noise spectroscopy (SNS), we derive analytic formulas for the observable noise spectra, and for the correlation functions among different hyperfine components, which give additional insight into the spin dynamics. The analytic results indicate a variety of distortions of the spin-noise spectrum relative to simpler models, including a broad spectral background that mimics optical shot noise, interference of noise contributions from the two ground-state hyperfine levels, noise reduction at the spin-precession frequency, and ``hiding'' of spin-noise power that can introduce a systematic error in noise-based calibrations, e.g., for spin-squeezing experiments.

Measurement of the bound-electron g-factor difference in coupled ions

Quantum electrodynamics (QED) is one of the most fundamental theories of physics and has been shown to be in excellent agreement with experimental results1–5. In particular, measurements of the electron’s magnetic moment (or g factor) of highly charged ions in Penning traps provide a stringent probe for QED, which allows testing of the standard model in the strongest electromagnetic fields6. When studying the differences between isotopes, many common QED contributions cancel owing to the identical electron configuration, making it possible to resolve the intricate effects stemming from the nuclear differences. Experimentally, however, this quickly becomes limited, particularly by the precision of the ion masses or the magnetic field stability7. Here we report on a measurement technique that overcomes these limitations by co-trapping two highly charged ions and measuring the difference in their g factors directly. We apply a dual Ramsey-type measurement scheme with the ions locked on a common magnetron orbit8, separated by only a few hundred micrometres, to coherently extract the spin precession frequency difference. We have measured the isotopic shift of the bound-electron g factor of the isotopes 20Ne9+ and 22Ne9+ to 0.56-parts-per-trillion (5.6 × 10−13) precision relative to their g factors, an improvement of about two orders of magnitude compared with state-of-the-art techniques7. This resolves the QED contribution to the nuclear recoil, accurately validates the corresponding theory and offers an alternative approach to set constraints on new physics.

Indirect control of the 29SiV− nuclear spin in diamond

Coherent control and optical readout of the electron spin of the $^{29}$SiV$^{-}$ center in diamond has been demonstrated in literature, with exciting prospects for implementations as memory nodes and spin qubits. Nuclear spins may be even better suited for many applications in quantum information processing due to their long coherence times. Control of the $^{29}$SiV$^{-}$ nuclear spin using conventional NMR techniques is feasible, albeit at slow kilohertz rates due to the nuclear spin's low gyromagnetic ratio. In this work we theoretically demonstrate how indirect control using the electron spin-orbit effect can be employed for high-speed, megahertz control of the $^{29}$Si nuclear spin. We discuss the impact of the nuclear spin precession frequency on gate times and the exciting possibility of all optical nuclear spin control.

Generating Stellar Obliquity in Systems with Broken Protoplanetary Disks

Recent advances in submillimeter observations of young circumstellar nebulae have opened an unprecedented window into the structure of protoplanetary disks that has revealed the surprising ubiquity of broken and misaligned disks. In this work, we demonstrate that such disks are capable of torquing the spin axis of their host star, representing a hitherto unexplored pathway by which stellar obliquities may be generated. The basis of this mechanism is a crossing of the stellar spin precession and inner disk regression frequencies, resulting in adiabatic excitation of the stellar obliquity. We derive analytical expressions for the characteristic frequencies of the inner disk and star as a function of the disk gap boundaries and place an approximate limit on the disk architectures for which frequency crossing and the resulting obliquity excitation are expected, thereby illustrating the efficacy of this model. Cumulatively, our results support the emerging consensus that significant spin–orbit misalignments are an expected outcome of planet formation.

Tidal effect on the gyroscopic precession around a compact star

General relativistic effects around massive astrophysical objects can be captured using a test gyro orbiting the object in a circular geodesic. This paper discusses how the tidal field due to a companion object affects the spin precession frequency and orbital angular velocity of a spinning gyro orbiting around a compact astrophysical object. The precession frequency is studied in a region of space around the central object using a perturbative approach. The central object is either a neutron star or a white dwarf in this study. The test gyro is any planetary or asteroid-like object orbiting a neutron star or a white dwarf. Moreover, the companion object that causes the tidal field can be a neutron star, white dwarf or a stellar black hole. It is seen that the tidal effect significantly affects the spacetime around the central object, which affects the gyro precession frequency and the orbital angular velocity. Slow rotation approximation has been considered for the central object, which creates negligible deformation. The change in the gyro’s precession frequency and the orbital angular velocity due to the tidal field increases with an increase in the companion object’s mass and decreases as the separation between the central star and the companion star increases. The tidal effect also varies with the stiffness of the equation of state of matter describing the host star. The lower the compactness of the host star, the greater is the tidal response; thus the greater is the change in the gyro’s precession and angular velocity of the geodesic.

Nonequilibrium sub-10 nm spin-wave soliton formation in FePt nanoparticles.

Magnetic nanoparticles such as FePt in the L10 phase are the bedrock of our current data storage technology. As the grains become smaller to keep up with technological demands, the superparamagnetic limit calls for materials with higher magnetocrystalline anisotropy. This, in turn, reduces the magnetic exchange length to just a few nanometers, enabling magnetic structures to be induced within the nanoparticles. Here, we describe the existence of spin-wave solitons, dynamic localized bound states of spin-wave excitations, in FePt nanoparticles. We show with time-resolved x-ray diffraction and micromagnetic modeling that spin-wave solitons of sub-10 nm sizes form out of the demagnetized state following femtosecond laser excitation. The measured soliton spin precession frequency of 0.1 THz positions this system as a platform to develop novel miniature devices.

Spin Precession in the Gravity Wave Analogue Black Hole Spacetime

It was predicted that the spin precession frequency of a stationary gyroscope shows various anomalies in the strong gravity regime if its orbit shrinks, and eventually, its precession frequency becomes arbitrarily high very close to the horizon of a rotating black hole. Considering the gravity waves of a flowing fluid with a vortex in a shallow basin, which acts as a rotating analogue black hole, one can observe the predicted strong gravity effect on the spin precession in the laboratory. Attaching a thread with the buoyant particles and anchoring it to the bottom of the fluid container with a short-length miniature chain, one can construct a simple local test gyroscope to measure the spin precession frequency in the vicinity of the gravity wave analogue black hole. The thread acts as the axis of the gyroscope. By regulating the orbital frequency of the test gyroscope, one can also measure the strong gravity Lense–Thirring effect and geodetic/de-Sitter effect with this experimental set-up as the special cases. For example, to measure the Lense–Thirring effect, the length of the miniature chain can be set to zero, so that the gyroscope becomes static. One can also measure the geodetic precession with this system by orbiting the test gyroscope in the so-called Keplerian frequency around the non-rotating analogue black hole that can be constructed by making the rotation of the fluid/vortex negligible compared to its radial velocity.

Solid-state NMR signals at zero-to-ultra-low-field

Zero-to-ultra-low-field nuclear magnetic resonance (ZULF NMR) is fast emerging as a viable spectroscopic approach to study samples under conditions dominated by internal spin interactions. In the absence of the truncating effects of Zeeman interaction, the NMR signal is determined by J-coupling, dipole-dipole, and/or quadrupolar interactions. But, the low spin-precession frequencies and equilibrium spin polarisation in low external fields necessitate the use of special techniques for detecting the signals. In this article, spin evolution in ultra-low-field regime for various systems is studied and the expected NMR signals are evaluated for solid samples. The methodologies that can be used to make low-field detection feasible especially in case of solid samples are described.