Magnetic susceptibility and magnetization fluctuation measurements of mixed gadolinium-yttrium iron garnets

Eckel, Stephen; Sushkov, Alexander O.; Lamoreaux, S. K.

doi:10.1103/physrevb.79.014422

Cited by 23 publications

(11 citation statements)

References 37 publications

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“…The physical mechanisms leading to dissipation in the form of Gilbert damping are the same ones through which S interacts with the lattice and the transverse spin components are averaged [50][51][52]. According to the FDT, in the lowfrequency limit ω ≪ k B T , the spectral density of transverse spin fluctuations at frequency ω is given by…”

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confidence: 99%

Precessing Ferromagnetic Needle Magnetometer

2016

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A ferromagnetic needle is predicted to precess about the magnetic field axis at a Larmor frequency Ω under conditions where its intrinsic spin dominates over its rotational angular momentum, N ≫ IΩ (I is the moment of inertia of the needle about the precession axis and N is the number of polarized spins in the needle). In this regime the needle behaves as a gyroscope with spin N maintained along the easy axis of the needle by the crystalline and shape anisotropy. A precessing ferromagnetic needle is a correlated system of N spins which can be used to measure magnetic fields for long times. In principle, by taking advantage of rapid averaging of quantum uncertainty, the sensitivity of a precessing needle magnetometer can far surpass that of magnetometers based on spin precession of atoms in the gas phase. Under conditions where noise from coupling to the environment is subdominant, the scaling with measurement time t of the quantum-and detectionlimited magnetometric sensitivity is t −3/2 . The phenomenon of ferromagnetic needle precession may be of particular interest for precision measurements testing fundamental physics.For an ensemble of N independent particles prepared in a coherent superposition of quantum states, the standard quantum limit (SQL) on the precision of a measurement of the phase φ is given byafter time t ≫ 1/Γ rel , where Γ rel is the relaxation rate of the coherence. Equation (1) represents a random walk in phase with step size 1/ √ N consisting of Γ rel t steps. In cases where the goal is to measure a frequency Ω = φ/t, there is an analogous SQL on the precision of a frequency measurement,For a measurement subject to the SQL, the minimum possible measurement uncertainty is obtained when Γ rel is made as small as possible. In the limit where Γ rel → 0, the precision becomes constrained by the duration of the measurement, so in Eqs. (1) and (2), Γ rel is replaced by 1/t. However, if the particles' time evolution is correlated, the SQL can be circumvented for times shorter than the coherence time (1/Γ rel ) [2][3][4]. Extensive experimental efforts involving quantum entanglement, squeezed states, and quantum nondemolition (QND) measurement strategies have been made to take advantage of this potential improvement in measurement sensitivity [5][6][7][8]. In this Letter we draw attention to a system which can, in principle, surpass the SQL on measurement of spin precession in a different way: by rapid averaging of quantum uncertainty.In particular, we consider the measurement of magnetic fields. The most precise magnetic field measurements are based on the techniques of optical atomic magnetometry [9, 10]: N atomic spins are optically polarized and their precession in a magnetic field B is measured using optical rotation of probe light [11]. Depending on its magnitude, the value of B is either extracted from measurement of the Larmor frequency Ω = gµ B B/ or the accrued spin precession angle φ = Ωt if φ ≪ 1 during the measurement time t (g is the Landé g-factor and µ B is the Bohr magneton). Optica...

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confidence: 99%

Precessing Ferromagnetic Needle Magnetometer

2016

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“…From Fig. 7b, the EDS analysis confirms the empirical formulation to be GdY 2 Fe 5 O 12 , which suggests that the magnetic sample under test is a mixed yttrium gadolinium iron garnet [20][21][22] Gd x Y (3−x) Fe 5 O 12 with x = 1. The sensor was fabricated with the dimensions described in "Design of proposed double-layer sensor" section on a Taconic RF 35 substrate using an LPKF Protomat E33 milling machine.…”

Section: Sample Characterization and Sensor Fabricationmentioning

confidence: 53%

Novel MNZ-type microwave sensor for testing magnetodielectric materials

Jha

Delmonte

Lamęcki

et al. 2020

Sci Rep

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A novel microwave sensor with the mu-near-zero (MNZ) property is proposed for testing magnetodielectric material at 4.5 GHz. The sensor has a double-layer design consisting of a microstrip line and a metal strip with vias on layers 1 and 2, respectively. The proposed sensor can detect a unit change in relative permittivity and relative permeability with a difference in the operating frequency of 45 MHz and 78 MHz, respectively. The MNZ sensor is fabricated and assembled on two layers of Taconic RF-35 substrate, with thicknesses of 0.51 mm and 1.52 mm, respectively, for the measurement of the sample under test using a vector network analyzer. The dielectric and magnetic properties of two standard dielectric materials (Taconic CER-10 and Rogers TMM13i) and of yttrium–gadolinium iron garnet are measured at microwave frequencies. The results are found to be in good agreement with the values available in the literature, which shows the applicability of the prototype for sensing of magnetodielectric materials.

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“…The presence of excessive magnetization noise in the magnetic material under study can degrade magnetic field sensitivity and weaken the achievable EDM limit [5,11]. The setup described above was used to look for magnetization noise in Eu 0.5 Ba 0.5 TiO 3 at 4.2 K, but it was found that this noise is at or below the SQUID sensitivity.…”

Section: E Magnetic Susceptibility and Magnetization Noisementioning

confidence: 99%

The prospects for an electron electric dipole moment search with ferroelectric (Eu,Ba)TiO$_3$ ceramics

Sushkov,

Eckel,

Lamoreaux

2009

Preprint

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We propose to use ferroelectric (Eu,Ba)TiO3 ceramics just above their magnetic ordering temperature for a sensitive electron electric dipole moment search. We have synthesized a number of such ceramics with various Eu concentrations and measured their properties relevant for such a search: permeability, magnetization noise, and ferroelectric hysteresis loops. The results of our measurements indicate that a search for the electron electric dipole moment with Eu0.5Ba0.5TiO3 should lead to an order of magnitude improvement on the current best limit.

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Magnetic susceptibility and magnetization fluctuation measurements of mixed gadolinium-yttrium iron garnets

Cited by 23 publications

References 37 publications

Precessing Ferromagnetic Needle Magnetometer

Precessing Ferromagnetic Needle Magnetometer

Novel MNZ-type microwave sensor for testing magnetodielectric materials

The prospects for an electron electric dipole moment search with ferroelectric (Eu,Ba)TiO$_3$ ceramics

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