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AC Measurement of Magnetic Susceptibility

AC Measurement of Magnetic SusceptibilityPhysics 401, Fall 2014 Eugene V. CollaOutline Ferromagnetism Measurement of the Magnetic properties of the materials Lab experimental setup and experiments Some results 11/10/20142 Ferromagnetism. Definition. Some materials below a certain temperature (Tc) give rise to the Magnetic field in absence of an applied magnetization is called spontaneous, the phenomenon ferromagnetism and materials exhibiting this feature ferromagnetics. The main parameter of the ferromagnetic phase transition is spontaneous magnetization T/Tc Ms(T)/Ms(0)Typical behavior of spontaneous magnetization as function of temperature11/10/20143 Ferromagnetic materials. AleksandrStoletov(1839 1896) MaterialCurie temp. (K)Co1388Fe1043Fe2O3*948 FeOFe2O3*858 NiOFe2O3*858 MgOFe2O3*713 MnBi630Ni627 MnSb587 MnOFe2O3*573Y3Fe5O12*560 CrO2386 MnAs318Gd292 Stoletov curve11/10/20144 Stoletovperformed pioneer works in area of ferromagnetic materials but better known by his research in photoelectric Domains.

AC Measurement of Magnetic Susceptibility Physics 401, Fall 2014 Eugene V. Colla. Outline

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Transcription of AC Measurement of Magnetic Susceptibility

1 AC Measurement of Magnetic SusceptibilityPhysics 401, Fall 2014 Eugene V. CollaOutline Ferromagnetism Measurement of the Magnetic properties of the materials Lab experimental setup and experiments Some results 11/10/20142 Ferromagnetism. Definition. Some materials below a certain temperature (Tc) give rise to the Magnetic field in absence of an applied magnetization is called spontaneous, the phenomenon ferromagnetism and materials exhibiting this feature ferromagnetics. The main parameter of the ferromagnetic phase transition is spontaneous magnetization T/Tc Ms(T)/Ms(0)Typical behavior of spontaneous magnetization as function of temperature11/10/20143 Ferromagnetic materials. AleksandrStoletov(1839 1896) MaterialCurie temp. (K)Co1388Fe1043Fe2O3*948 FeOFe2O3*858 NiOFe2O3*858 MgOFe2O3*713 MnBi630Ni627 MnSb587 MnOFe2O3*573Y3Fe5O12*560 CrO2386 MnAs318Gd292 Stoletov curve11/10/20144 Stoletovperformed pioneer works in area of ferromagnetic materials but better known by his research in photoelectric Domains.

2 Hysteresis ~MsM=011/10/20145* Courtesy microscopeCourtesy of University of Uppsala (Sweden)11/10/20146 DomainsCourtesyofWikipedia11/10/20147 Moving domain walls in a grain of silicon steel caused by an increasing external Magnetic fieldHysteresis Loops. Remagnetizationloses = = =V*Loop_areaEnergy of the Magnetic fieldBy cycling around the loop11/10/20148 Hard materials. memoryHard drives, floppy, Magnetic tapePermanent magnets11/10/20149 Soft materials. transformersChokes, inductors11/10/20141011/10/201411 Magnetic Field, Susceptibility etc. 0BH M B Magnetic inductionM magnetization, in general M(H)MH Magnetic Susceptibility , in general (H) 001rBHHH 001; rrdBdBdHdH Modulation Spectroscopy11/10/201412()Bf H 01H = H + H sin tH001H = H + H sin t01dfB = f(H ) +(H sin t)+.

3 DHB0Bw()BfH H1=const ~ Measuring the Magnetic permeability0000,(, )(1(, ))HdBHHdHw w w ByapplyingasmallmodulationoftheHfieldwec anmeasurethederivativeoftheB-Hhysteresis loopordependenceofthemagneticpermeabilit yonHfield11/10/201413 Setup #1. Investigation of the hysteresis #1. Investigation of the hysteresis = Major/minor loops. DemagnetizationBHsaturation80160240-1000 100timeH( )Waveform of H-field11/10 ( )Idc (A)tim e (m in)0204060-2-1012 IDC (A)time (min)Demagnetization of 4C65 toroid from Ferroxcube11/10/201417 Hysteresis (BRdenotesremanenceandHCisthecoercivity) .CourtesyZureks(Wikipedia)11/10/201418 Measuring the Magnetic permeability-200-100010020002468101214 '/1000H (A/m) max~12700-1001081012H (A/m)05001000-4-2024 IDC (A)time (s)DCcurrentprofileandmagneticpermeabili tyofMagneticsZW44715TC11/10/201419 From permeability to B-H hysteresis loopStep#1.

4 Performing one fast IDC scan the based on the result preparing the smart IDC profileECE storeroom unknown material Sample #50200400600800-101 IDC (A)time (s)Step#2. Performing precise scan the. Plotting raw data (mV)IDC (A)Voltage units measured by SR830 Current in primary coil in A11/10/201420 From permeability to B-H hysteresis loopStep#3. What we are measuring? measures emfon the pickup coil;lock indVB Sdt Here Ipis ac current in primary coil L3; = ( ) 11/10/201421 From permeability to B-H hysteresis loopStep#3. What we are measuring? coil of Npturns supplied by current Ipcreates Magnetic field H and flux d For toroid: = R2<r < R12121 ln22 RRRI N tdrI N tdH darR da=dr*t11/10/201422 From permeability to B-H hysteresis loopStep#3.

5 What we are measuring? ppickupNN I tRNdR Total flux detected by pickup coil: Inductance of the toroid: 00; ()rLLLiLI 0201ln2pickuppNN tRLR Npand Ipnumber of turns of AC primary coil and AC rmscurrent 11/10/201423 From permeability to B-H hysteresis (mV)IDC (A) = 0plock inrdIVLdt -400-20002004000100020003000400050006000 'H (A/m)11/10/201424 From permeability to B-H hysteresis loop0000()()rdBHHHdH Step#4. From r(H) to B-HAfter integrating -400-20002004000100020003000400050006000 'H (A/m) (T)H (A/m)0()()rB HH dH 11/10/201425 Software issue11/10/201426 Icon on the desktop1stweek experiment2nd week experimentDemagnetization B-H measurementPreparation of the profile of the experimentSoftware issueMeasuring profile preparationExample of simple protocolAdvanced profile-400-2000200400010002000300040005 0006000 'H (A/m)Software issueMeasurement Window Lock-in amplifier response The profile of the appliedDC currentStructure of the data file (B-H experiment)Data analysis using Origin 11/10/201429To calculate the permeability better to use the template.

6 \\engr-file-03\phyinst\APL Courses\PHYCS401\Common\Origin templates\AC Magnetic Lab\ dataParametersCalculated resultsIt does not contain the equations you have to write themData analysis using Origin. Integrating. 0()()rB HH dH 11/10/201430 Data analysis using Origin. Integrating. 0()()rB HH dH offset 11/10/201431Ms-MsReferences Information about Magnetic materials can be found in : \\engr-file-03\phyinst\APL Courses\PHYCS401\Experiments\AC_Magnetiz ation\ Magnetic Materials SR830 manual: \\engr-file-03\phyinst\APL Courses\PHYCS401\Common\EquipmentManuals \


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