Layered 5d transition metal dichalcogenide (TMD) IrTe2 is distinguished from the traditional TMDs (such as NbSe2) by the existence of multiple CDW-like stripe phases and superconductivity at low temperatures. Despite of intensive studies, there is st
ill no consensus on the physical origin of the stripe phases or even the ground state modulation for this 5d material. Here, we present atomic-scale evidence from scanning tunneling microscopy and spectroscopy (STM/STS), that the ground state of IrTe2 is a q=1/6 stripe phase, identical to that of the Se-doped compound. Furthermore, our data suggest that the multiple transitions and stripe phases are driven by the intralayer Ir-Ir dimerization that competes against the interlayer Te-Te bonding. The competition results in a unified phase diagram with a series of hierarchical modulated stripe phases, strikingly similar to the renowned devils staircase phenomena.
Space charge effects, being one of the most significant collective effects, play an important role in high intensity cyclotrons. However, for cyclotrons with small turn separation, other existing effects are of equal importance. Interactions of radia
lly neighboring bunches are also present, but their combined effects has not yet been investigated in any great detail. In this paper, a new particle in cell based self-consistent numerical simulation model is presented for the first time. The model covers neighboring bunch effects and is implemented in the three-dimensional object-oriented parallel code OPAL-cycl, a flavor of the OPAL framework. We discuss this model together with its implementation and validation. Simulation results are presented from the PSI 590 MeV Ring Cyclotron in the context of the ongoing high intensity upgrade program, which aims to provide a beam power of 1.8 MW (CW) at the target destination.
