Pressure-tuned insulator to metal transition inEu2Ir2O7

Abstract

We have studied the effect of pressure on the pyrochlore iridate Eu 2 Ir 2 O 7 , which, at ambient pressure, has a thermally driven insulator to metal transition at T MI ∼ 120 K. As a function of pressure, the insulating gap closes, apparently continuously near P ∼ 6 GPa. However, rather than T MI going to zero as expected, the insulating ground state crosses over to a metallic state with a negative temperature coefficient of resistivity, suggesting that these ground states have a novel character. The high-temperature state also crosses over near 6 GPa from an incoherent to a conventional metal, implying that there is a connection between the high-and the low-temperature states.

X-ray scattering study of pyrochlore iridates: Crystal structure, electronic, and magnetic excitations

“…In addition, we observe no pressureinduced structural transitions or symmetry changes for applied pressures up to 17 GPa. This result has direct implications for recent high pressure transport studies by Tafti et al 28 , which reported pressure-induced metalinsulator (low temperature) or metal-incoherent metal (high temperature) transitions in Eu 2 Ir 2 O 7 around 6-8 GPa. Since our experimental results have demonstrated that no structural anomalies occur in the vicinity of the critical pressure, we can conclude that these pressureinduced transitions are likely driven by purely electronic effects.…”

Optical Spectroscopic Studies of the Metal-Insulator Transition Driven by All-In–All-Out Magnetic Ordering in5dPyrochloreCd2OsSohn1, Jeong2, Jin3 et al. 2015Phys. Rev. Lett.265310View full textAdd to dashboardCite

“…Recently, MITs and antiferromagnetic ordering in 5d pyrochlores, A 2 B 2 O 7 (B ¼ Ir, Os), have received much attention due to their strong correlation and the key role they play in novel phases. The MITs in these compounds [3][4][5][6][7][8] reportedly are prompted by the emergence of magnetic ordering. Such magnetism-driven MITs are expected to induce exotic phenomena, including a Weyl semimetal [9][10][11][12] and quantum criticality [13] in rare-earth pyrochlore iridates.…”

Continuous transition between antiferromagnetic insulator and paramagnetic metal in the pyrochlore iridate Eu2Ir2O7Ishikawa1, O’Farrell2, Nakatsuji3 2012Phys. Rev. B112181082View full textAdd to dashboardCite

“…In particular, rare-earth pyrochlore iridates R 2 Ir 2 O 7 (R = rare-earth elements) provide an ideal class of materials because they have been reported to show a variety of transport and magnetic behaviors [5][6][7][8] , varying from a correlated metal [9][10][11] to an insulator 12,13 depending on the ionic radius of rare-earth elements. They are also attractive because the one hole nature of Ir 4+ 5d t 5 2g state simplifies the electronic structure and allows further in depth comparison between experiment and theory.…”

“…13 According to the theoretical prediction, it is likely that the diffusive metallic phase under pressure may well correspond to the topological semi-metallic phase. Further study on the properties of this state under pressure is highly desired to elucidate the exotic nature of the ground state.…”