Electrical transport measurement is the most common technique in pulsed magnetic fieldsr. Bothdccurrent andacdigital lock-in techniques are available for measurements of magneto-resistance or Hall effects at Wuhan National High Magnetic Field Center. Up to date, extensive scientific experiments have been successfully performed.

1) Configurations

Magnetic fields: 50-75 T

Pulse duration: 50-2250 ms

Temperature: 0.5-400 K

2) Operation principle

(1)dccurrent technique

A standard four-wire method is adopted for wiring the sample. Constant-current pulse is applied to reduce heating effect of the sample as shown in Fig.1. Two pulse shots are made in the experiment by comparison with different bias current to further eliminate the spurious signals of the background.

Figure 1 Illustration ofdccurrent technique in pulsed fields

(2)acdigital lock-in technique

The principle of this technique is to digitize all high-frequency signals in pulsed fields and analyze the data afterwards using appropriate software. The measuring circuit is shown in Fig. 2. High-frequency sine wave voltage is applied in the pulse shot on the sample and a shunt resistance. High-frequency signals V_xx, V_xy, and V_shuntare measured simultaneously by five-wire method in the experiment and the data are analyzed subsequently using the digital lock-in program. Sample current is obtained by measuring the voltage of the shunt resistance,I=V_shunt/R_shunt,Thus, the magneto-resistance and Hall resistance with magnetic fields are given by (gain of the preamplifer is 1 in this case),R_XX=V_XX/I; R_XY=V_XY/I

Figure 2 The measuring circuit ofacdigital lock-in technique

3) main instruments

National Instruments PXI-5105, PCI 5922, 6244

Keithley 2400, 2182, 2000, 6221, 6487

Stanford Research System SR850 Digital lock-in amplifier, SR560 amplifier

LakeShore 330, 335

4) Related publications

1. Zuo, HK, Bao, JK, Liu, Y,Wang, JH, Jin, Z, Xia, ZC, Li, L, Xu, Z, Kang, J, Zhu, ZW, Cao, GH, Temperature and angular dependence of the upper critical field in K2Cr3As3. PHYSICAL REVIEW B. 95, 014502 (2017)

2. Yanwen Liu, Xiang Yuan, Cheng Zhang, Zhao Jin, Awadhesh Narayan, Chen Luo, Zhigang Chen, Lei Yang, Jin Zou, Xing Wu, Stefano Sanvito, Zhengcai Xia, Liang Li, Zhong Wang & Faxian Xiu, Zeeman splitting and dynamical mass generation in Dirac semimetal ZrTe5, NATURE COMM., 7:12516(2016)

3. Z Jin, Z-C Xia, M Wei, J-H Yang, B Chen, S Huang, C Shang, H Wu, X-X Zhang, J-W Huang，and Z-W Ouyang，3D spin-flop transition in enhanced 2D layered structure single crystalline TlCo2Se2，J. Phys.: Condens. Matter 28 (2016) 396002

Staff contact:Zengwei Zhu, Zhengcai Xia, Junfeng Wang