关键词: single crystal growth, narrow band system, electrical transport, high mobilities

Abstract: We report the growth of high-quality single crystals of RhP$_{2}$, and systematically study its structure and physical properties by transport, magnetism, and heat capacity measurements. Single-crystal x-ray diffraction reveals that RhP$_{2}$ adopts a monoclinic structure with the cell parameters a=5.7347(10) Å, b=5.7804(11) Å, and c=5.8222(11) Å, space group $P2_{1}/c$ (No. 14). The electrical resistivity $\rho (T)$ measurements indicate that RhP$_{2}$ exhibits narrow-bandgap behavior with the activation energies of 223.1 meV and 27.4 meV for two distinct regions, respectively. The temperature-dependent Hall effect measurements show electron domain transport behavior with a low charge carrier concentration. We find that RhP$_{2}$ has a high mobility $\mu_{\rm e}\sim210$ cm$^{2}$$\cdot$V$^{-1}$$\cdot$s$^{-1}$ with carrier concentrations $n_{\rm e}\sim 3.3\times 10^{18}$ cm$^{-3}$ at 300 K with a narrow-bandgap feature. The high mobility $\mu_{\rm e}$ reaches the maximum of approximately 340 cm$^{2}$$\cdot$V$^{-1}$$\cdot$s$^{-1}$ with carrier concentrations $n_{\rm e}\sim 2\times 10^{18}$ cm$^{-3}$ at 100 K. No magnetic phase transitions are observed from the susceptibility $\chi (T)$ and specific heat $C_{\rm p}(T)$ measurements of RhP$_{2}$. Our results not only provide effective potential as a material platform for studying exotic physical properties and electron band structures but also motivate further exploration of their potential photovoltaic and optoelectronic applications.

Key words: single crystal growth, narrow band system, electrical transport, high mobilities