Wheatstone bridge technique for magnetostriction measurements

Sullivan, Michael

doi:10.1063/1.1136225

Cited by 12 publications

(4 citation statements)

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“…Magnetostriction was measured by attaching strain gauges in a temperature-compensating Wheatstone bridge type setup (to minimize thermal drifts) using the lock-in amplifier technique described previously. 1, 14 The resolution of our lock-in method is ~0.04-0.1 ppm strain, and is typically <0.1 ppm. To measure strains normal to the discs, microstrain gauges were attached on the cylindrical surface of the sample, as described elsewhere.…”

Section: Methodsmentioning

confidence: 99%

Contracting non-Joulian magnets

et al. 2017

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Recently, non-volume conserving or non-Joulian magnetostriction has been reported in Fe-Ga alloys [Nature 521, 340 (2015); ibid., 538 416 (2016)] that increase their volume by expanding in magnetic fields. Here we report the complementary set of contracting non-Joulian crystals (Fe-Ge, Fe-Al) that decrease their volume. Results provide the critical compositional degree-of-freedom necessary for designing new alloys (beyond the initially reported Fe-Ga alloys) and establish this new family of functional materials based on non-Joulian magnetostriction.

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Section: Methodsmentioning

confidence: 99%

Contracting non-Joulian magnets

et al. 2017

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“…High-resolution, high thermal stability magnetostriction measurements are made by attaching strain gauges on single crystal discs, using lock-in amplifier with Wheatstone bridge circuit. [10] Although it is relatively easy to set up a "basic" magnetostriction measurement system, it is non-trivial to measure these strains at high-resolution and without thermal drifts. This is because any factor (e.g., thermal fluctuations) that causes a change in length of the resistive grid of a strain gauge produces an artefact.…”

Section: Methodsmentioning

confidence: 99%

Non‐Joulian Magnetostriction and Non‐Joulian Magnetism

Chopra

Ravishankar

Pacifico

et al. 2018

Physica Status Solidi (b)

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Complementing volume‐conserving Joule magnetostriction (JM), the non‐Joulian magnetostriction (NJM) phenomenon has recently been discovered whose hallmark is change in volume of the crystals in magnetic fields. This article reviews the unique set of non‐Joulian properties that are so non‐conforming relative to conventional magnets that they merit the designation of a distinctly new class of (functional) magnets. This review distils key aspects of non‐Joulian magneto‐elasticity and magnetism, including the sign of volume change (contracting or expanding); the orientation dependence of volume change that is key to realizing large volume changes (remarkably, this volume‐anisotropy coexists with a seemingly isotropic magnetization response for all crystal axes); and a digital coercivity landscape unlike that seen in conventional magnets. NJM lay undiscovered for nearly two decades because prior literature assumed, without experimental foundation, that iron‐based alloys obeyed volume‐conserving JM. Measurements now show that volume change is inherent across wide composition ranges, occurring in both quenched, metastable, and inexorably slow‐cooled, equilibrated crystals. While not essential, quenching promotes long‐range periodicity of magneto‐elastic gradients with enhanced NJM. Another objective is to “frame” Joulian‐to‐non‐Joulian behavior within a single framework of magnetically responsive, wave‐like elastic medium in which approach to homogeneity yields the limiting case of JM; in fact, gradient magnet‐elasticity is indispensable to describing non‐Joulian magnetism. A consequential auxiliary finding is the large differences in intrinsic magneto‐elastic constants for seemingly equivalent crystal axes, consistent with gradient magneto‐elasticity. Consequentially, a sizeable literature that previously characterized these crystals using volume‐conserving assumption and framework of phenomenological magnetostriction theory of homogeneous cubic crystals is rendered moot, and unreliable for high‐fidelity applications.

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“…The VSM vibrating frequency of the sample was 55 Hz at 0.2 mm amplitude. Magnetostriction can be measured by the straingauge technique 24 or by a modified STM 25 . In the present case, we used commercially available strain gauges (Micro-Measurements Group Inc. U. S. A), made from temperature compensated 120-Ω Karma foil with negligible magnetoresistance.…”

Section: Experimental Methodsmentioning

confidence: 99%

Magnetostrictive Fe73Ga27 nanocontacts for low-field conductance switching

Mohanan

Kuntz

Berg

et al. 2016

Applied Physics Letters

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Abstract:The electrical conductance G of magnetostrictive nanocontacts made from Galfenol (Fe 73 Ga 27 ) can be reproducibly switched between 'on' and 'off' states in a low magnetic field of ~ 20 -30 mT at 10 K. The switching behavior is in agreement with the magnetic field dependence of the magnetostriction inferred from the magnetization behavior, causing a positive magnetostrictive strain along the magnetic field. The repeated magnetic-field cycling leads to a stable contact geometry and to a robust contact configuration with a very low hysteresis of ~ 1 mT between opening and closing the contact due to a training effect. Non-integral multiples of the conductance quantum G 0 observed for G > G 0 are attributed to electron backscattering at defect sites in the electrodes near the contact interface. When the contact is closed either mechanically or by magnetic field, the conductance shows an exponential behavior below G 0 due to electron tunneling. This allows to estimate the magnetostriction  = 4 x 10 -5 at 10 K. The results demonstrate that such magnetostrictive devices are suitable for the remote control of the conductance by low magnetic fields in future nanotechnology applications.2

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Wheatstone bridge technique for magnetostriction measurements

Abstract: A basic Wheatstone bridge, with additional electronic instrumentation, has been used in the measurement of magnetostriction. This method allows a resolution of approximately 10% on measurements of magnetostrictions less than 0.75 parts per million.

Cited by 12 publications

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Contracting non-Joulian magnets

Contracting non-Joulian magnets

Non‐Joulian Magnetostriction and Non‐Joulian Magnetism

Magnetostrictive Fe73Ga27 nanocontacts for low-field conductance switching

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