Frequency Dependency of the Delta-E Effect and the Sensitivity of Delta-E Effect Magnetic Field Sensors

In recent years the delta-E effect has been used for detecting low frequency and low amplitude magnetic fields. Delta-E effect sensors utilize a forced mechanical resonator that is detuned by the delta-E effect upon application of a magnetic field. Typical frequencies of operation are from several k...

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Main Authors: Benjamin Spetzler, Elizaveta V. Golubeva, Cai Müller, Jeffrey McCord, Franz Faupel
Format: Article
Language:English
Published: MDPI AG 2019-11-01
Series:Sensors
Subjects:
Online Access:https://www.mdpi.com/1424-8220/19/21/4769
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author Benjamin Spetzler
Elizaveta V. Golubeva
Cai Müller
Jeffrey McCord
Franz Faupel
author_facet Benjamin Spetzler
Elizaveta V. Golubeva
Cai Müller
Jeffrey McCord
Franz Faupel
author_sort Benjamin Spetzler
collection DOAJ
description In recent years the delta-E effect has been used for detecting low frequency and low amplitude magnetic fields. Delta-E effect sensors utilize a forced mechanical resonator that is detuned by the delta-E effect upon application of a magnetic field. Typical frequencies of operation are from several kHz to the upper MHz regime. Different models have been used to describe the delta-E effect in those devices, but the frequency dependency has mainly been neglected. With this work we present a simple description of the delta-E effect as a function of the differential magnetic susceptibility <inline-formula> <math display="inline"> <semantics> <mi>&#967;</mi> </semantics> </math> </inline-formula> of the magnetic material. We derive an analytical expression for <inline-formula> <math display="inline"> <semantics> <mi>&#967;</mi> </semantics> </math> </inline-formula> that permits describing the frequency dependency of the delta-E effect of the Young&#8217;s modulus and the magnetic sensitivity. Calculations are compared with measurements on soft-magnetic <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mrow> <mrow> <mo>(</mo> <mrow> <msub> <mrow> <mi>Fe</mi> </mrow> <mrow> <mn>90</mn> </mrow> </msub> <msub> <mrow> <mi>Co</mi> </mrow> <mrow> <mn>10</mn> </mrow> </msub> </mrow> <mo>)</mo> </mrow> </mrow> <mrow> <mn>78</mn> </mrow> </msub> <msub> <mrow> <mi>Si</mi> </mrow> <mrow> <mn>12</mn> </mrow> </msub> <msub> <mi mathvariant="normal">B</mi> <mrow> <mn>10</mn> </mrow> </msub> </mrow> </semantics> </math> </inline-formula> thin films. We show that the frequency of operation can have a strong influence on the delta-E effect and the magnetic sensitivity of delta-E effect sensors. Overall, the delta-E effect reduces with increasing frequency and results in a stiffening of the Young&#8217;s modulus above the ferromagnetic resonance frequency. The details depend on the Gilbert damping. Whereas for large Gilbert damping the sensitivity continuously decreases with frequency, typical damping values result in an amplification close to the ferromagnetic resonance frequency.
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spelling doaj.art-aa946e1d54254694acac5f0546b5abe32022-12-22T04:23:23ZengMDPI AGSensors1424-82202019-11-011921476910.3390/s19214769s19214769Frequency Dependency of the Delta-E Effect and the Sensitivity of Delta-E Effect Magnetic Field SensorsBenjamin Spetzler0Elizaveta V. Golubeva1Cai Müller2Jeffrey McCord3Franz Faupel4Kiel University, 24118 Kiel, GermanyKiel University, 24118 Kiel, GermanyKiel University, 24118 Kiel, GermanyKiel University, 24118 Kiel, GermanyKiel University, 24118 Kiel, GermanyIn recent years the delta-E effect has been used for detecting low frequency and low amplitude magnetic fields. Delta-E effect sensors utilize a forced mechanical resonator that is detuned by the delta-E effect upon application of a magnetic field. Typical frequencies of operation are from several kHz to the upper MHz regime. Different models have been used to describe the delta-E effect in those devices, but the frequency dependency has mainly been neglected. With this work we present a simple description of the delta-E effect as a function of the differential magnetic susceptibility <inline-formula> <math display="inline"> <semantics> <mi>&#967;</mi> </semantics> </math> </inline-formula> of the magnetic material. We derive an analytical expression for <inline-formula> <math display="inline"> <semantics> <mi>&#967;</mi> </semantics> </math> </inline-formula> that permits describing the frequency dependency of the delta-E effect of the Young&#8217;s modulus and the magnetic sensitivity. Calculations are compared with measurements on soft-magnetic <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mrow> <mrow> <mo>(</mo> <mrow> <msub> <mrow> <mi>Fe</mi> </mrow> <mrow> <mn>90</mn> </mrow> </msub> <msub> <mrow> <mi>Co</mi> </mrow> <mrow> <mn>10</mn> </mrow> </msub> </mrow> <mo>)</mo> </mrow> </mrow> <mrow> <mn>78</mn> </mrow> </msub> <msub> <mrow> <mi>Si</mi> </mrow> <mrow> <mn>12</mn> </mrow> </msub> <msub> <mi mathvariant="normal">B</mi> <mrow> <mn>10</mn> </mrow> </msub> </mrow> </semantics> </math> </inline-formula> thin films. We show that the frequency of operation can have a strong influence on the delta-E effect and the magnetic sensitivity of delta-E effect sensors. Overall, the delta-E effect reduces with increasing frequency and results in a stiffening of the Young&#8217;s modulus above the ferromagnetic resonance frequency. The details depend on the Gilbert damping. Whereas for large Gilbert damping the sensitivity continuously decreases with frequency, typical damping values result in an amplification close to the ferromagnetic resonance frequency.https://www.mdpi.com/1424-8220/19/21/4769delta-e effectmagnetoelasticityresonatorsmagnetic field sensingdynamic susceptibilitysurface acoustic wave (saw)
spellingShingle Benjamin Spetzler
Elizaveta V. Golubeva
Cai Müller
Jeffrey McCord
Franz Faupel
Frequency Dependency of the Delta-E Effect and the Sensitivity of Delta-E Effect Magnetic Field Sensors
Sensors
delta-e effect
magnetoelasticity
resonators
magnetic field sensing
dynamic susceptibility
surface acoustic wave (saw)
title Frequency Dependency of the Delta-E Effect and the Sensitivity of Delta-E Effect Magnetic Field Sensors
title_full Frequency Dependency of the Delta-E Effect and the Sensitivity of Delta-E Effect Magnetic Field Sensors
title_fullStr Frequency Dependency of the Delta-E Effect and the Sensitivity of Delta-E Effect Magnetic Field Sensors
title_full_unstemmed Frequency Dependency of the Delta-E Effect and the Sensitivity of Delta-E Effect Magnetic Field Sensors
title_short Frequency Dependency of the Delta-E Effect and the Sensitivity of Delta-E Effect Magnetic Field Sensors
title_sort frequency dependency of the delta e effect and the sensitivity of delta e effect magnetic field sensors
topic delta-e effect
magnetoelasticity
resonators
magnetic field sensing
dynamic susceptibility
surface acoustic wave (saw)
url https://www.mdpi.com/1424-8220/19/21/4769
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AT elizavetavgolubeva frequencydependencyofthedeltaeeffectandthesensitivityofdeltaeeffectmagneticfieldsensors
AT caimuller frequencydependencyofthedeltaeeffectandthesensitivityofdeltaeeffectmagneticfieldsensors
AT jeffreymccord frequencydependencyofthedeltaeeffectandthesensitivityofdeltaeeffectmagneticfieldsensors
AT franzfaupel frequencydependencyofthedeltaeeffectandthesensitivityofdeltaeeffectmagneticfieldsensors