Examining the surface phase diagram of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>IrTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> with photoemission
M. Rumo, C. W. Nicholson, Aki Pulkkinen, B. Hildebrand, Geoffroy Kremer, Björn Salzmann, M.-L. Mottas, K. Y., E Laine Wong, Michael K. L. Man, Keshav M. Dani, B. Barbiellini, Matthias Muntwiler, T. Jaouen, Fabian O. von Rohr, Claude Monney
Abstract
In the transition metal dichalcogenide ${\mathrm{IrTe}}_{2}$, low-temperature charge-ordered phase transitions involving Ir dimers lead to the occurrence of stripe phases of different periodicities, and nearly degenerate energies. Bulk-sensitive measurements have shown that, upon cooling, ${\mathrm{IrTe}}_{2}$ undergoes two such first-order transitions to $(5\ifmmode\times\else\texttimes\fi{}1\ifmmode\times\else\texttimes\fi{}5)$ and $(8\ifmmode\times\else\texttimes\fi{}1\ifmmode\times\else\texttimes\fi{}8)$ reconstructed phases at ${T}_{{c}_{1}}\ensuremath{\sim}280$ K and ${T}_{{c}_{2}}\ensuremath{\sim}180$ K, respectively. Here, using surface sensitive probes of the electronic structure of ${\mathrm{IrTe}}_{2}$, we reveal the first-order phase transition at ${T}_{{c}_{3}}=165$ K to the $(6\ifmmode\times\else\texttimes\fi{}1)$ stripes phase, previously proposed to be the surface ground state. This is achieved by combining x-ray photoemission spectroscopy and angle-resolved photoemission spectroscopy, which give access to the evolution of stripe domains and a particular surface state, the energy of which is dependent on the Ir dimer length. By performing measurements over a full thermal cycle, we also report the complete hysteresis of all these phases.