Chiral Unitary Quantum Phase Transition in 2H-Fe $$_x$$ x TaSe $$_2$$ 2

Abstract

We have observed a metal-insulator transition of a quasi-two dimensional electronic system in transition metal dichalcogenide 2H-TaSe 2 caused by doping iron. The sheet resistance of 2H-Fe x TaSe 2 (0 ≤ x ≤ 0.120) single crystals rises about 10 6 times with the increasing of x at the lowest temperature. We investigated the temperature dependence of the resistance and found a metal-insulator transition with a critical sheet resistance 11.7 ± 5.4 kΩ. The critical exponent of the localization length ν is estimated 0.31 ± 0.18. The values of the critical sheet resistance and ν are accordant to those of the chiral unitary class (less than h/1.49e 2 = 17.3 kΩ and 0.35 ± 0.03, respectively). We suggest that 2H-Fe x TaSe 2 is classified as the chiral unitary class, not as standard unitary class.