Magnetic property measurement system (mpms)

The series of compounds Sm_1−xLa_xNiC₂ (0 ≤ x ≤ 1) and Sm_1−yLu_yNiC₂ (0 ≤ y ≤ 0.4) were synthesized by the arc-melting technique, using constituent elements of purity 99.9% or higher. The weight loss after arc melting was less than 1%, indicating that the nominal concentration is close to the actual alloying level. Since WDS analysis corroborates this conclusion, the nominal concentration was used throughout this manuscript. The arc-melted samples were annealed at 1173K for ten days in a sealed evacuated quartz tube. The annealed samples were quenched in NaCl-ice water mixture. Structural characterization was performed by the powder x-ray diffraction (PXRD) method using a Rigaku diffractometer with Cu Kα radiation. The lattice parameters of the samples were determined by LeBail profile refinements of PXRD carried out using the FULLPROF software27 . Resistivity measurements were performed using a standard four probe technique employing a Quantum Design Physical Property Measurement System (PPMS). The contacts were made by spot welding of platinum wires on the sample surface. Heat capacity was measured in temperature range 1.9 K < T < 300 K at fields up to 9 T by using the thermal relaxation technique (PPMS system). Magnetic measurements were carried out using a Quantum Design Magnetic Property Measurement System (MPMS).

The four-probe technique was used for the longitudinal resistance, R_xx, and the Hall resistance, R_xy, was acquired by the standard method. The magneto-resistance and magnetization measurements were carried out using Quantum Design Inc.’s Physical Properties Measurement System (PPMS. The magnetic properties of the samples were characterized using Quantum Design Inc.’s Magnetic Property Measurement System (MPMS). The device is able to detect small signals (≤10⁻⁸ emu) with great accuracy using the superconducting quantum interference device (SQUID) magnetometry technology. The MPMS can access temperatures as low as 1.8 K and can ramp the magnetic field up to 7T. The ‘soft’ point-contact spectroscopy was performed in an He-3 refrigerator. The current is past through a thin Au wire to the sample through a 30 μm tiny drop of Ag nano-particle epoxy paint. To acquire the dI/dV data, a small AC current is superimposed with a sweeping DC current.

Polycrystalline sample of DyVO₄ has been prepared by the conventional solid state route by using the precursors Dy₂O₃ and VO₂ from Sigma Aldrich, with 99.99% purity. The initial reagents were taken in the stochiometric ratio, grinded and given first heat treatment at 800° C, followed by final sintering at 900 °C. Room temperature powder X-ray diffraction (XRD) was performed at room temperature in the range 10°–90° using Rigaku diffraction with Cu Kα (λ = 1.54). FullProf Suite software was used to perform the refinement of the X-ray diffraction data. Fig. S1 of the Supplementary Information shows the Rietveld refinement of the XRD pattern. The compound belongs to Zircon family, crystallizing in the tetragonal structure with space group I 41/a m d and is in single phase. T and H dependent magnetic measurements were performed using the Magnetic Property Measurement System (MPMS) from Quantum Design, USA. Physical Property Measurement System (PPMS), Quantum Design, USA was used to measure field dependent C.

Electric-field control of magnetism was performed using a Quantum Design magnetic property measurement system (MPMS) with in situ electric fields. The resistance of MTJs was acquired via a homemade electromagnet system using the four-probe method with a Keithley 6221 current source and a Keithley 2182 nanovolt meter. The voltage applied to the PMN-PT was generated by a Keithley 6517 electrometer. The duration of the used voltage pulses in our present work is about 5 s and the width of voltage pulses in theory can be less than 20 ns for our devices (Supplementary Note 3). Furthermore, this duration of the voltage pulses can be less than 10 ns (ref. ^{11 (link)}) using FE films, which needs to be explored in future experiments. All the measurements were carried out at room temperature.

Polycrystalline sample of TbVO₄ was synthesised by the conventional solid state reaction method by using high purity Tb₂O₃ and VO₂ from Sigma Aldrich with 99.9% purity. The initial materials in stochiometric ratio were grinded and given heat treatment at 800 °C. The obtained product was palettized and sintered at 800 °C. Room temperature powder XRD was performed in the range (10°–90°) using Rigaku diffraction with Cu Kα (λ = 1.54) radiation. The crystal structure was refined by the Rietveld method using the FullProf Suite software. Magnetic field and temperature dependent magnetic measurements in the temperature range 1.8–300 K were performed using the Magnetic Property Measurement System (MPMS) from Quantum Design, USA. Physical Property Measurement System (PPMS), Quantum Design, USA was used to measure temperature dependent heat capacity at different fields up to 70 kOe.

We measured the a.c. susceptibility χ′ using a superconducting quantum interference device magnetometer (Quantum Design, Magnetic Property Measurement System (MPMS)) equipped with a home-built sample holder to enable the application of electric fields. The frequency and excitation amplitude of the a.c. susceptibility measurement are 700 Hz and 3.8 Oe, respectively. The leakage current is less than 1 pA during the measurement at 30 kV cm⁻¹. The cooling rate utilized in this study was fixed at 10 K min⁻¹. The typical measurement time per measurement point was a few minutes. In the χ′–E measurement (Fig. 4b), we set a target temperature, then applied sufficiently high magnetic fields to form the ferromagnetic state, and finally reduced the magnetic field to the target point (350 Oe).