Hall effect in ytterbium hydrides

Abstract This study addressed Hall effect measurements in the nonstoichiometric α-phase ytterbium dihydride (α-YbH2±δ) and β-phase ytterbium trihydride (β-YbH3−δ) films. We have prepared orthorhombic α-YbH2.05 and cubic β-YbH2.7 polycrystalline films using hydrogenation of precursor Yb films formed in a molecular-beam process. The observed positive Hall coefficients indicate p-type conduction in α-YbH2.05 and β-YbH2.7. Experimental results in the orthorhombic α-phase suggest a conduction-type change depending on compositions around the stoichiometric composition of YbH2. Possible conduction mechanisms in these nonstoichiometric ytterbium hydrides are discussed from the viewpoint of modulation of electronic structures by hydrogen vacancies.