Hysteresis Loop Measurements Research Articles

Electrode free hysteresis loop measurement of small dimensional ferroelectric materials

As the basic characterization for ferroelectric material, hysteresis loop measurement based on Sawyer-Tower circuit has restrictions of electrodes, parallel plate capacitor structure and complex compensating circuit, which cannot satisfy the demand for characterization of small dimensional ferroelectric materials. In this work, a new measuring method of hysteresis loop is presented based on probes and high resolution semiconductor parameter analyzer. The capacitance of BiFeO3 film between two probes under sweeping bias voltage was measured and transformed into polarization, and the test under light illumination showed similar hysteresis loop. The hysteresis loop of small lead zirconate titanate ceramic particle was also measured. This study gives much freedom to obtain the hysteresis loop between any two points of small dimensional ferroelectric material of any shape, and to get rid of electrodes, and to conduct in situ measurement under external field.

Effective magnetic path length in Epstein frame test of electrical steels.

The effective magnetic path length lm for a 25cm Epstein frame test is studied on the basis of a relevant demagnetizing model and determined by a comparative measurement of dc and ac hysteresis loops at each value of peak flux density Bp, with the field recorded by H-coils placed above the mid-section of the limbs or calculated from the magnetizing current. The obtained Bp and frequency dependences of lm for testing core loss Ps and peak field Hp of an electrical steel are explained in terms of differential susceptibility along the measured loops and demagnetizing and eddy-current effects on local magnetization processes.

Observation of domain structure in non-collinear antiferromagnetic Mn3Sn thin films by magneto-optical Kerr effect

We perform hysteresis-loop measurement and domain imaging for (11¯00)-oriented D019-Mn3+xSn1-x (−0.11≤x≤0.14) thin films using the magneto-optical Kerr effect (MOKE) and compare it with the anomalous Hall effect (AHE) measurement. We obtain a large Kerr rotation angle of 10 mdeg, comparable with bulk single-crystal Mn3Sn. The composition x dependence of AHE and MOKE shows a similar trend, suggesting the same origin, i.e., the non-vanishing Berry curvature in the momentum space. Magnetic domain observation at the saturated state shows that x dependence of AHE and MOKE is explained by the amount of the reversible area that crucially depends on the crystalline structure of the film. Furthermore, in-depth observation of the reversal process reveals that the reversal starts with nucleation of sub-micrometer-scale domains dispersed in the film, followed by domain expansion, where the domain wall preferentially propagates along the [112¯0] direction. Our study provides a basic understanding of the spatial evolution of the reversal of the chiral-spin structure in non-collinear antiferromagnetic thin films.

The Influence of Microstructure on the Electromagnetic Behavior of Carbon Steel Wires

This paper describes the relations between microstructure, mechanical properties, and electromagnetic behavior of carbon steel wires submitted to different thermomechanical treatments. The electrical resistivity and bulk magnetic properties are determined through resistivity measurements down to 2 K and magnetic hysteresis loop measurements. In addition, magnetic domains are imaged by magnetic force microscopy despite the complex microstructures. The electromagnetic properties are mainly related to changes in the volume fraction, morphology, and distribution of the cementite phase within the α-ferrite matrix. Electrical conductivity and magnetic permeability increase in the order of martensite, tempered martensite, pearlite, proeutectoid ferrite-pearlite, spheroidite, and ferrite microstructures. The increase in carbon concentration enhances the electrons localization at atomic sites, assisting the covalent character of Fe–C interatomic bonds and thereby reducing conductivity. Moreover, the α-Fe3C interfaces that act as a physical barrier for dislocation slip in ferrite, affecting also the main free-paths for conductive electrons and magnetic domain walls displacements within the materials. As the electromagnetic behavior of steels results from individual contributions of microstructural elements that are often intrinsically related to one another, a careful interpretation of both electrical and magnetic responses is critical for a proper application of quality and process monitoring methods of carbon steel wires.

An Improved Approach to Calculate Eddy Current Loss in Soft Magnetic Materials Based on Measured Hysteresis Loops

The paper presents a study of the influence of magnetic hysteresis on macroscopic eddy current losses. Usually, this loss is calculated within many simplifying assumptions, of which the most striking is not only neglecting the hysteresis, but also the nonlinearity of the material. To check how such simplifications affect the results, the loss was calculated taking into account the hysteresis phenomenon for several materials. For this purpose, an algorithm for solving Maxwell’s equations with magnetic characteristics given as a family of measured hysteresis loops was constructed. A new method for conversion between H and B fields using the measured hysteresis loops was also proposed. The results of calculations for three materials show that the eddy current loss calculated with magnetic hysteresis taken into account are smaller than those calculated via the classical formula obtained for linear materials. For the tested materials, the differences reach up to around 30%, depending on frequency, magnetic flux density and thickness of electrical sheet. This may result, among others, in erroneous determination of the excess loss in Bertotti’s approach.

High-throughput characterization of the cyclic response of Ti-6Al-4V using spherical microindentation stress–strain protocols

This paper presents novel high-throughput spherical microindentation measurement and analyses protocols for the cyclic response of metal samples. These protocols are aimed at rapid screening of large design spaces encountered in the development of advanced metal alloys. They involve the measurement of cyclic load-depth hysteresis loops in spherical microindentation, their conversion to cyclic indentation stress–strain hysteresis loops, and the extraction of an indentation cyclic stress–strain curve. The proposed spherical microindentation measurement and analyses protocols are demonstrated on samples of Ti-6Al-4V. The indentation measurements are compared against the measurements obtained on the same material in standard uniaxial stress tests in both monotonic and cyclic loading. The cyclic indentation stress–strain measurements correlated well with the measurements from the standard uniaxial stress tests.

Magnetic Properties of Hybrid Inorganic-organic Flexible Nanofibers

Polypyrrole nanofibers (PPy-NFs) had prepared via chemical oxidation of pyrrole monomer by Iron (III) chloride in the presence of methyl orange. As well as, Nanomagnetic particles of Co0.8Mn0.2Fe2O4 and Zn0.8Mn0.2Fe2O4 had synthesized by the hydrothermal autoclave reactor after use co-precipitation technique. The PPy-NFs nanocomposite that obtained from decorating of PPy-NFs with Nanomagnetic particles. The XRD studied showed that the (PPy-NFs) is non-crystalline and the average crystallite size of Co0.8Mn0.2Fe2O4 and Zn0.8Mn0.2Fe2O4 were 8.54 and 14.47 nm respectively. These two belong to single phase cubic spinel. FESEM studies exhibit that PPy has a nanofibers structure with distinct diameters and most the magnetic nanoparticles had homogeneous distribution and had sphere form. The saturation magnetization (Ms) increased with increasing ferrite content in the nanocomposite samples, according to magnetic hysteresis loop measurements. As its increases in pure ferrite samples by increases cobalt ions. The Ms Values of Co0.8Mn0.2Fe2O4, Zn0.8Mn0.2Fe2O4 and PPy-NFs were 41.15 emu/g, 10.13 emu/g and 14.95 emu/g respectively.

Experimental evaluation and theoretical analysis of the mechanical properties of ferromagnetic materials using the magnetic hysteresis properties

The magnetic hysteresis properties of ferromagnetic materials have been investigated by experimental measurement and theoretical analysis for mechanical property evaluation. A modified Jiles-Atherton (JA) model is proposed considering both the frequency and microscopic dependence of the hysteresis properties. Dynamic hysteresis experiments of ferromagnetic specimens with different hardness values were performed to measure the hysteresis loops. Microscopic measurements of the specimens were performed to obtain the grain size and dislocation density, which were introduced into the dynamic JA model to calculate the theoretical hysteresis loops. The genetic algorithm was used to inverse the basic parameters of the JA model by matching the theoretical hysteresis loops with the experimentally measured hysteresis loops. Two magnetic parameters (the coercivity and power-law coefficient) were extracted from the hysteresis loops for mechanical property evaluation of ferromagnetic materials. It was found that the proposed JA model can be used for theoretical analysis of the influence of the microstructure on the magnetic hysteresis properties, and the coercivity and power-law coefficient can be used for mechanical property evaluation of ferromagnetic specimens. The research reveals the influence of microstructure on the mechanical properties (hardness) and magnetic characteristic parameters of ferromagnetic materials.

Concentration dependence of yield stress, thixotropy, and viscoelasticity rheological behavior of lithium-ion battery slurry

The rheological properties of electrode slurry are mainly influenced by the concentration, which further affects the Lithium-ion batteries (LIBs) quality and manufacturing processes. In this work, various methods including steady-state shear, creep, rheological model fitting, hysteresis loop, and small amplitude oscillatory shear (SAOS) measurement were employed to investigate the concentration-dependent rheological behaviors of slurry, in particular its yield stress, thixotropy, and viscoelasticity. Results show that the difference in yield stress obtained from varying methods is observed, in which the yield stresses measured by the SAOS test are closer to the steady-state value due to its advantage that non-destructive property at small deformations only causes minimum disturbance. The improvement of slurry concentration enhances the bonding strength between particles, thereby resulting in an increase of yield stress and thixotropy, and a decrease of the time scale of transient behavior during the creep process. In oscillatory shear measurement, both storage and loss modulus are concentration-dependent, while yielding and strain stiffening corresponding to critical strains exhibit concentration-independent. In addition, the increase in concentration leads to a more pronounced strain stiffening behavior and a lower characteristic frequency as well as a longer relaxation time. Understanding the relationship between concentration and rheological behaviors will be helpful for material design, preparation, and production in different stages.

Large exchange bias due to spin-glass behavior in hexagonal-YMn0.8Fe0.2O3 thin film

We report spin-glass (SG) behavior and large exchange bias effect at low temperature (∼2 K) in Fe-doped hexagonal-YMnO3 (YMn0.8Fe0.2O3) thin film. The thin films of YMnO3 and YMn0.8Fe0.2O3 are deposited on Pt(111)/Al2O3(0001) substrate by pulsed laser deposition method. The temperature dependent magnetization measurements show a characteristic peak for YMn0.8Fe0.2O3 film indicating the presence of SG state as confirmed by memory effect measurements. The hysteresis loops reveal high coercivity in YMn0.8Fe0.2O3 as compared to YMnO3 thin film. Field cooled hysteresis loop measurements at 2 K show the presence of exchange bias in YMn0.8Fe0.2O3 thin film. Maximum exchange bias of ∼909 Oe has been observed for hysteresis loop with cooling field of 20 kOe at 2 K. The exchange bias is further confirmed by training effect as well as negative and positive field cooled hysteresis loops. Exchange bias effect in YMn0.8Fe0.2O3 thin film can be attributed to the interaction between spin-glass/Anti-ferromagnetic phases.

Modified copper zinc ferrite nanoparticles doped with Zr ions for hyperthermia applications

The problem of the present work is to synthesize a nanomagnetic material with low TC below 45 °C and its particle size below 30 nm to be appropriate material for convert magnetic loss into heat energy. A series of Cu0.4Zn0.6+yZryFe2–2yO4 nanoparticles compositions where y = (0.05, 0.1) were synthesized via citrate sol–gel method. The prepared samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The grains were observed from SEM confirming the crystalline structure of the ferrite which was detected by X-ray diffraction. Magnetic hysteresis loop measurements illustrate that materials exhibit soft magnetic properties at low Zr content, while at higher Zr content all materials behave as superparamagnetically without any saturation magnetization Ms. The initial magnetic permeability ({mu }_{i}) at frequency 10 kHz as a function of temperature was measured. A sudden change in {mu }_{i} appears around Curie temperature, making our samples good candidates for magnetic temperature transducer (MTT) devices. The DC resistivity for sample at y = 0.05, 0.1 was studied. The resistivity decreases linearly with increasing temperature within the given range of temperature up to 666 K for all samples. The dielectric constant of all samples is nearly independent on temperature through the range of 450 to 600 K which is a common character of ferrites. The dielectric loss was found to increase by increasing temperature, which may be related to the increase in AC conductivity. Hyperthermia measurements show the maximum specific power loss and temperature increase were 26 w/gr and 43 °C, respectively, for sample containing Zr = 0.05, after 2 min of measurements. One of the real applications of the material is that it is used as an effective method in tumor treatment by exposing the patient to external magnetic field.

Contact stiffness of jointed interfaces: A comparison of dynamic substructuring techniques with frictional hysteresis measurements

The tangential contact stiffness is an important parameter used in non-linear dynamic analyses of jointed structures since it can strongly affect the prediction of resonance frequencies. Many experimental techniques are available for contact stiffness estimations, but the reliability of such estimations remains unknown due to a lack of comparative studies. This paper proposes a comparative study of contact stiffness measurements obtained with two experimental techniques: hysteresis loop measurements and Frequency Based Substructuring (FBS). Hysteresis loops are traditionally measured with dedicated friction test rigs to provide, amongst others, contact stiffness estimations through local interface measurements. The assumption with hysteresis measurements is that the measured parameters are independent of the dynamics of the test rig and can therefore be used as input for analyses of other structures, as long as loading conditions and contact interfaces are comparable. An alternative approach to identify the contact stiffness is FBS, which uses information from the overall system dynamics. FBS has the advantage that it can be applied to any structure, without the need of building ad-hoc test rigs, consequently giving a structure-specific information. Despite this advantage over hysteresis measurements, it is as of yet not well understood how accurately FBS can extract contact stiffness values. This paper presents FBS measurements and hysteresis loop measurements performed simultaneously on the same contact interface of a traditional high-frequency friction rig during vibration, thus enabling a cross-validation of the results of both techniques. This novel comparison validates FBS approaches against local hysteresis measurements and shows the strengths and limitations of both experimental methods, making it possible to improve the current understanding of the contact stiffness of jointed structures.

Micromagnetism and microstructure – tailoring of high-performance permanent magnets

Abstract The magnetic properties of hard magnetic materials are closely connected to their microstructure. The complexity of this correlation is demonstrated for the two most promising permanent magnet (pm) materials at present, namely nanocrystalline RE2Fe14B (RE = Nd,Pr) and nanostructured Sm2(Co, Cu, Fe, Zr)17. In both cases the detailed analysis of the microstructure – property interaction by means of different high-resolution electron microscopy techniques, hysteresis loop measurements and the theory of micromagnetism results in a quantitative interpretation of the occurring hardening mechanisms, enabling a quite specific tailoring of optimized magnetic properties up to elevated temperatures.

Ferroelectricity in a semiconducting all-inorganic halide perovskite.

Ferroelectric semiconductors are rare materials with both spontaneous polarizations and visible light absorptions that are promising for designing functional photoferroelectrics, such as optical switches and ferroelectric photovoltaics. The emerging halide perovskites with remarkable semiconducting properties also have the potential of being ferroelectric, yet the evidence of robust ferroelectricity in the typical three-dimensional hybrid halide perovskites has been elusive. Here, we report on the investigation of ferroelectricity in all-inorganic halide perovskites, CsGeX3, with bandgaps of 1.6 to 3.3 eV. Their ferroelectricity originates from the lone pair stereochemical activity in Ge (II) that promotes the ion displacement. This gives rise to their spontaneous polarizations of ~10 to 20 μC/cm2, evidenced by both ab initio calculations and key experiments including atomic-level ionic displacement vector mapping and ferroelectric hysteresis loop measurement. Furthermore, characteristic ferroelectric domain patterns on the well-defined CsGeBr3 nanoplates are imaged with both piezo-response force microscopy and nonlinear optical microscopic method.

Angular-dependent magnetic properties of chemically synthesized single crystalline Co nanowires

Angular-dependent measurements of magnetic properties could point the way for understating reversal modes of anisotropic nanoobjects for use in next generation of more powerful and permanent information storage devices. However, such measurements have been significantly less considered for chemically synthesized nanowires. Here, single crystalline hexagonal close-packed Co nanowires with an average length and diameter of 220 and 12 nm, respectively, are synthesized using a solvothermal method in a non-polar solvent. The angular-dependent (0° ≤θ ≤ 90°) magnetic properties are carefully studied by hysteresis loop measurements and first-order reversal curve (FORC) analysis after aligning the Co nanowires oriented along [001] direction in epoxy. While randomly oriented Co nanowires have a coercivity (Hc) and squareness (Sq) of 4.3 kOe and 0.54, respectively, they show enhanced magnetic properties (Hc = 7.9 kOe and Sq = 0.78) after alignment at θ = 0°. The FORC analysis indicates the formation of by-products such as nanoparticles and low aspect ratio nanorods in the synthesis of the Co nanowires, which are confirmed by high-resolution transmission electron microscopy. The variation of coercive field distribution (ΔHcFORC) as a function of θ is studied, demonstrating a continuous increase in (ΔHcFORC) for θ > 45°. This indicates that the aligned Co nanowires with high crystallinity may reverse their magnetization through a domain wall mode, being in accordance with the literature on the magnetization reversal mechanism taking place in electrochemically fabricated Co nanowire arrays.

Construction of core-shell Fe3O4@GO-CoPc photo-Fenton catalyst for superior removal of tetracycline: The role of GO in promotion of H2O2 to •OH conversion

A novel core-shell structured Fe3O4@GO-CoPc magnetic catalyst, which is with magnetite (Fe3O4) as the core, graphene oxide (GO) as the interlayer and cobalt-phthalocyanine (CoPc) as the shell, was successfully prepared and used as a heterogeneous photo-Fenton catalyst for tetracycline (TC) degradation in this work. The core-shell structure of the catalyst was confirmed by XRD, FTIR, SEM and TEM. BET and magnetic hysteresis loops measurements indicated that Fe3O4@GO-CoPc catalyst owned large specific surface area and could be easily recovered under an external magnetic field. Meanwhile, the experimental results of TC degradation demonstrated that the photo-Fenton efficiency of Fe3O4@GO-CoPc was excellent. When the reaction time was 120 min, TC could be degraded almost completely in the photo-Fenton system with Fe3O4@GO-CoPc. The high photo-Fenton catalytic activity of Fe3O4@GO-CoPc could be resulted from the effective transfer of photo-generated electrons between CoPc and Fe3O4 by GO. Moreover, the main reaction species, •OH, O2•-, 1O2 and h+, were verified by the analysis of active species in this system. Finally, the mechanism analyses and quantitative analysis results of active species indicated that the introduction of GO accelerated the cycle between Fe(II) and Fe(III) as well as improved the effective utilization of H2O2 (the efficiency of conversion of H2O2 to •OH).

Neural Network Modeling of Arbitrary Hysteresis Processes: Application to GO Ferromagnetic Steel

A computationally efficient hysteresis model, based on a standalone deep neural network, with the capability of reproducing the evolution of the magnetization under arbitrary excitations, is here presented and applied in the simulation of a commercial grain-oriented electrical steel sheet. The main novelty of the proposed approach is to embed the past history dependence, typical of hysteretic materials, in the neural net, and to illustrate an optimized training procedure. Firstly, an experimental investigation was carried out on a sample of commercial GO steel by means of an Epstein equipment, in agreement with the international standard. Then, the traditional Preisach model, identified only using three measured symmetric hysteresis loops, was exploited to generate the training set. Once the network was trained, it was validated with the reproduction of the other measured hysteresis loops and further hysteresis processes obtained by the Preisach simulations. The model implementation at a low level of abstraction shows a very high computational speed and minimal memory allocation, allowing a possible coupling with finite-element analysis (FEA).

Mechanical and magnetic properties of TRIP690 steel strengthened by strain-induced martensite

The sensitivity of the induced magnetic signals to microstructures makes it possible to characterize nondestructively the mechanical properties of ferromagnetic materials. In this study, utilizing the hysteresis loop measurement and the magnetic Barkhausen noise measurement, the correlation between the mechanical and the magnetic properties of low-alloy multiphase transformation-induced plasticity (TRIP) steel after plastic deformation was investigated, then the strength of the TRIP steel after plastic deformation was characterized. The results showed that, as the strain level increased from 0 to 0.2, the martensite volume fraction of TRIP690 steel increased from 0.78% to 3.64% which contributed to the enhancement of mechanical properties and the change of magnetic properties, and in particular, hardness and tensile strength had linearly increased by approximately 42% and 20%, respectively. Meanwhile, the peak value of the magnetic Barkhausen noise signal (MBNS) increased linearly with the increasing strain levels, the coercivity increased rapidly and then slowly, while the susceptibility decreased exponentially. By theoretically deriving the effects of the ferromagnetic phase volume fraction, dislocation density and residual stress of the TRIP690 steel on susceptibility and coercivity, the variation of the MBNSs under the influence of phase transformation, dislocation and residual stress was analyzed. The above non-destructive magnetic technique makes it possible to evaluate the mechanical response of the TRIP steel after plastic deformation, which allows it to be further applied to the quality evaluation of steel parts in stamping, such as body-in-white for the automotive industry.

Magnetic properties of TbMn0.98Fe0.02O3 single crystal

This paper is focused on the study of magneto crystalline anisotropy which we performed on oriented TbMn0.98Fe0.02O3 single crystal by magnetization and AC susceptibility measurements. Our measurements revealed huge magneto crystalline anisotropy with respect to main crystallographic axes. The paramagnetic Weiss temperature θp spans a broad range of values which can indicate the strong magnetocrystalline anisotropy in the system. Easy magnetization axis is c-axis and b-axis is hard magnetic axis. The magnetic phase transitions at TN, Tlock and T1 are connected with anomalies in magnetization and AC susceptibility measurements performed along b-axis. Field induced magnetic transitions were observed at 2 K in the case of a sinusoidally modulated collinear magnetic structure for magnetization measurements along a-axis and c-axis. Hysteresis loops measurements indicate suppression of Tb3+ ordering in high magnetic field which depends on crystal orientation. In respect to iron doping our results resemble and extend results obtained on powdered crystals. Iron doping shifts both TN and Tlock to lower temperatures, antiferromagnetic JAF interaction in ac-plane decreases leaving barely changed ferromagnetic interaction JF. The critical field of the field induced phase transition increases with iron doping.

Measurement of coercivity of soft magnetic materials in open magnetic circuit by pump-probe rubidium atomic magnetometer

<sec>We report an experimental device and method of measuring the coercivity of soft magnetic material in an open magnetic circuit by using a pump-probe rubidium atomic magnetometer. The experimental device consists of a background magnetic field generation module, a pump-probe atomic magnetometer, a soft magnetic material magnetization and demagnetization module, and a software in a computer. The uniform background magnetic field ranging from 200 nT to 20000 nT along the <i>z</i>-axis at the rubidium bubble’s position is generated by a current carrying coil which is placed in a five-layer magnetic shielding cylinder. The saturation magnetization and demagnetization of soft magnetic material are realized by the soft magnetic sample magnetization and demagnetization module, respectively, which consists of a sample chamber, a soft magnetic sample, a magnetizing coil, a precision current source and a sample transfer rod. The sample chamber is placed in the magnetic field uniform area of the magnetizing coil which is placed in the magnetic shielding cylinder, and the sample transfer rod is used to transfer the soft magnetic sample into the center of the magnetizing coil. Both the rubidium bubble and the soft magnetic sample are placed on the <i>z</i>-axis of the magnetic shielding cylinder, and their distance is greater than or equal to 10 cm. The axis of the magnetizing coil coincides with the axis of the magnetic shielding cylinder, which ensures that the background magnetic field, the magnetic field generated by the magnetizing coil, and the magnetic field generated by the soft magnetic sample at the rubidium bubble’s position are all parallel to the axis direction of the magnetic shielding cylinder. The software in the computer realizes the magnetization and demagnetization of the soft magnetic sample by controlling the current output by the precision current source to the magnetizing coil, and also controls the pump-probe atomic magnetometer to measure the magnetic field at the rubidium bubble’s position. When the soft magnetic sample is magnetized or demagnetized in cycles, the magnetic field generated by the soft magnetic sample at the rubidium bubble’s position is obtained by subtracting the magnetic field value measured in advance when the sample is not placed in the sample chamber from the magnetic field value measured at same current value when the sample is placed in the sample chamber. Note that the sample does not move during the hysteresis loop measurement. When the magnetization of the soft magnetic sample decreases from the saturation value to zero, the magnetic field generated by the soft magnetic sample at the rubidium bubble’s position is zero, and the average coercivity of the sample can be calculated from the hysteresis loop.</sec><sec>We use a superconducting quantum interference device (SQUID), a pump-detection rubidium atomic magnetometer and a Hall probe to measure the coercivity of the same permalloy strip sample, the average coercivities are 42.15 A/m, 40.632 A/m and 38.64 A/m, the biases of the hysteresis loops are 229.74 A/m, –0.95 A/m and –52.88 A/m, and the times of each measurement cycle are 9639 s, 1144 s, and 1630 s, respectively. The reproducibility of ten repeated measurements by using the pump-probe atomic magnetometer, expressed as relative standard deviation, is 0.16%, which is an order of magnitude higher than the counterparts from the methods described in China’s national standards GB/T 3656-2008 and GB/T 13888-2009. The accumulated drift of the biases of ten hysteresis loops measured by the pump-probe atomic magnetometer is 0.3 A/m. Based on the above experimental results, the coercivity measurement method by using the pump-probe atomic magnetometer has the advantages of no zero-point drift, good repeatability, fast measurement speed, and <i>in-situ</i> measurement, and has the potential applications in the basic research field and industrial field of magnetism.</sec>