Vibrating sample magnetometer and measurement method of magnetic property

A vibrating sample magnetometer comprising:

• a sample housing vibrating body to house a measurement sample and vibrate the measurement sample in a single direction;
• an excitation electromagnet to apply an external magnetic field H to the measurement sample;
• a pressure application device to apply pressure to the measurement sample;
• a pressure detector to measure the applied pressure;
• a processor;
• and
• a memory to store a program which, when executed by the processor, performs operations of:
• detecting an induced voltage caused by vibration of the measurement sample magnetized by the excitation electromagnet to acquire a magnetic property, the magnetic property indicating a relationship between a magnetic flux density B and the external magnetic field H, the magnetic flux density being a sum of magnetization of the measurement sample and the external magnetic field H;
• and
• controlling the external magnetic field H and the pressure, and sweeping the external magnetic field H, wherein
• the processor acquires the magnetic property under a first measurement condition in an unloaded state, and
• after applying the external magnetic field H to the measurement sample such that the external magnetic field H changes from zero (H=0) to a positive-side limit value Hlmt of the magnetic property acquisition unit while keeping a measurement condition of the measurement sample to the first measurement condition that is in the unloaded state, the processor sets the measurement condition of the measurement sample to a second measurement condition that is in a loaded state, sets, as a sweep start value Hs, a first magnetic field value that is a value of the external magnetic field H sufficiently weak to avoid restoring the magnetic property, sets a sweep end value He of the external magnetic field H to a negative-side limit value −Hlmt of the magnetic property acquisition unit, and acquires a demagnetization property that is the magnetic property,
• the processor further calculates a difference ΔB1 between the magnetic property under the first measurement condition and the magnetic property under the second measurement condition, and determines, from the difference ΔB1, the demagnetization property of the measurement sample to which pressure is applied, and
• the processor further acquires, after the acquiring under the second measurement condition, a magnetic property of the measurement sample under a third measurement condition where the measurement sample is unloaded after being subjected to a load, the third measurement condition including applying, via the excitation electromagnet of the vibrating sample magnetometer, a third external magnetic field to the measurement sample and vibrating the measurement sample, via the sample housing vibrating body, to induce the voltage, calculates a second difference between the magnetic property acquired under the first measurement condition and the magnetic property acquired under the third measurement condition and determines, via the processor, whether the second difference indicates an irreversible change in the magnetic property of the measurement sample due to being in the loaded state, and
• the first magnetic field value is smaller than a second magnetic field value that is a maximum magnetization force Hmax in the magnetic property obtained under the first measurement condition that is in the unloaded state.