Characteristic Fermi surfaces and charge density wave in SrAl 4 and related compounds with the BaAl 4 -type tetragonal structure

We succeeded in growing single crystals of SrAl4 and related compounds with the BaAl4-type tetragonal structure by the self-flux method, and measured the electrical resistivity, magnetic susceptibility, Hall coefficient, thermoelectric power, and de Haas–van Alphen (dHvA) effect. A plausible characteristic feature of the charge density wave (CDW) was observed below TCDW = 243 K in SrAl4. We also studied an effect of pressure on the electronic state in SrAl4 by measuring the electrical resistivity and thermoelectric power. TCDW is found to decrease with increasing pressure, with a rate of dTCDW/dP = −12.5 K/GPa. To clarify the Fermi surface nesting, we studied the Fermi surface in SrAl4, which is found to be different from the Fermi surfaces of the similar compounds SrGa4, BaGa4, and BaAl4 without CDW. The Fermi surfaces in these compounds were determined from the dHvA experiments, together with the energy band calculations.