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To generate long-duration pulsed magnetic fields with low energy consumption, we present a practical setup that implements an electromagnet made of high-purity copper (99.9999%). The resistance of the high-purity copper coil decreases from 171 mΩ (300 K) to 19.3 mΩ (77.3 K) and to below ∼0.15 mΩ (4.2 K), indicating a high residual resistance ratio of 1140 and a substantial reduction in Joule loss at low temperature. Using a 157.5 F electric-double-layer-capacitor bank with a charged voltage of 100 V, a pulsed magnetic field of 19.8 T with a total field duration of more than 1 s is generated. The field strength of the liquid helium-cooled high-purity copper coil is approximately double that of a liquid nitrogen-cooled one. The low resistance of the coil and the resultant low Joule heating effect explain the improvements in accessible field strength. The low electric energy used for field generation warrants further investigation on low-impedance pulsed magnets consisting of high-purity metals., (© 2023 Author(s). Published under an exclusive license by AIP Publishing.)

We report an experimental setup for simultaneously measuring specific heat and thermal conductivity in feedback-controlled pulsed magnetic fields of 50 ms duration at cryogenic temperatures. A stabilized magnetic field pulse obtained by the feedback control, which dramatically improves the thermal stability of the setup and sample, is used in combination with the flash method to obtain absolute values of thermal properties up to 37.2 T in the 22-16 K temperature range. We describe the experimental setup and demonstrate the performance of the present method with measurements on single-crystal samples of the geometrically frustrated quantum spin-dimer system SrCu2(BO3)2. Our proof-of-principle results show excellent agreement with data taken using a standard steady-state method, confirming the validity and convenience of the present approach., (© 2023 Author(s). Published under an exclusive license by AIP Publishing.)

We have developed a new calorimeter for measuring the thermodynamic properties in pulsed magnetic fields. Instrumental design is described along with the instrument construction details, including the sensitivity of a RuO 2 thermometer. Operation of the calorimeter is demonstrated by measuring the heat capacity of three samples: pure germanium, CeCu 2 Ge 2 , and κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Br, in pulsed fields up to 43.5 T. Obtaining field stability is key in measuring high-resolution heat capacity under pulsed fields. We also examine the performance of the calorimeter by employing two measurement techniques: the quasi-adiabatic and dual-slope techniques. We demonstrate that the calorimeter developed in this study is capable of performing high-resolution calorimetry in pulsed magnetic fields, which opens the door to new opportunities for high-field thermodynamic studies.

A pulsed power supply with a compact and low-cost electric-double-layer-capacitor (EDLC) is developed for generating pulsed magnetic fields with a long pulse duration of a few seconds. The system is demonstrated in three experimental setups using a 10.7 F- or 50 F-EDLC capacitor bank. By using the 10.7 F-EDLC capacitor bank with a 27 mm wide-bore magnet, the pulsed magnetic field with a peak field strength of 24.3 T and a pulse duration of ∼1 s is generated. The field profiles are reproduced in the theoretical calculations taking Joule heating into account. The calculations are also used to discuss possible variations of the field profile for future investigations.

A simple method for measuring electrical resistivity under destructive pulsed magnetic fields is presented. This method uses pick-up voltage as the power source to allow the measurement of the absolute value of resistivity in ultra-high magnetic fields above 100 T. The experimental setup and its operation are described in detail, and its performance is demonstrated using critical field measurements of thin-film FeSe 0.5 Te 0.5 samples. Possible scientific applications of this setup in high magnetic fields as well as in any other environment with a high field sweep rate are also discussed.

We describe the construction of a simple, compact, and cost-effective feedback system that produces flat-top field profiles in pulsed magnetic fields. This system is designed for use in conjunction with a typical capacitor-bank driven pulsed magnet and was tested using a 60-T pulsed magnet. With the developed feedback controller, we have demonstrated flat-top magnetic fields as high as 60.64 T with an excellent field stability of ±0.005 T. The result indicates that the flat-top pulsed magnetic field produced features high field stability and an accessible field strength. These features make this system useful for improving the resolution of data with signal averaging.

A new calorimeter for measurements of the heat capacity and magnetocaloric effect of small samples in pulsed magnetic fields is discussed for the exploration of thermal and thermodynamic properties at temperatures down to 2 K. We tested the method up to μ(0)H=50 T, but it could be extended to higher fields. For these measurements we used carefully calibrated bare-chip Cernox(®) and RuO(2) thermometers, and we present a comparison of their performances. The monotonic temperature and magnetic field dependences of the magnetoresistance of RuO(2) allow thermometry with a precision as good as ±4 mK at T=2 K. To test the performance of our calorimeter, heat capacity and magnetocaloric effect for the spin-dimer compound Sr(3)Cr(2)O(8) and the triangular lattice antiferromagnet RbFe(MoO(4))(2) are presented.