Stoichiometry control and electronic and transport properties of pyrochlore 
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 thin films

Yang, Wencao; Xie, Yizhu; Sun, Xing; Zhang, Xiaohang; Park, K.; Xue, Suqin; Li, Y. L.; Tao, Chin‐Wang; Jia, Q. X.; Losovyj, Yaroslav; Wang, H.; Heremans, J. J.; Zhang, S. X.

doi:10.1103/physrevmaterials.2.114206

Cited by 11 publications

(5 citation statements)

References 64 publications

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“…An example of this could be considered for the iridate pyrochlore Bi 2 Ir 2 O 7 , where interactions between the spin orbit coupling and strongly correlated electrons could lead to novel topological states. The ability to create lattice-mismatch precisely using these high entropy oxides can impact these interactions to access the regime where these topological states lie …”

Section: Resultsmentioning

confidence: 89%

“…The ability to create lattice-mismatch precisely using these high entropy oxides can impact these interactions to access the regime where these topological states lie. 26 The Mg 2 Ta 3 Ln 3 O 14 compounds all demonstrate paramagnetic behavior, with Ln = Eu showing Van Vleck paramagnetism. 27 Curie−Weiss (CW) fits were done on the series of powders, with the resulting values shown in Table 2.…”

Section: ■ Experimental Proceduresmentioning

confidence: 99%

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Discovery and Single Crystal Growth of High Entropy Pyrochlores

et al. 2020

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A family of high entropy oxides with the formula Mg2Ta3Ln3O14 (Ln = La, Pr, Nd, Sm, Eu, Gd) has been discovered and synthesized. Single crystals, 5 mm OD × 2.5 cm, for Ln = Nd have been grown using the laser optical floating zone technique. Crystal orientations are confirmed by Laue diffraction, and structure solutions were obtained via single crystal X-ray diffraction. The structure is found to be a partially disordered pyrochlore, space group Fd-3m, fractional chemical formula (Mg0.25Nd0.75)2(Mg0.25Ta0.75)2O7. Magnetization measurements indicate ordinary paramagnetic behavior in all compounds down to T = 2 K, except in the Eu variant which possesses Van Vleck paramagnetism. Specific heat measurements for Ln = Nd shows no phase transitions between T = 300 and 2 K. We demonstrate the ability to prepare magnetically disordered materials by substitution of Mg with Ni, Mn, and Co, demonstrating the flexibility of this family in accommodating defects. The stabilization of these compounds could be due to the entropy gain associated with defects, showcasing a “materials by design” approach by using disorder to stabilize novel magnetic and optical materials. Our work also demonstrates the feasibility of preparing high entropy oxides in single crystalline form.

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Section: Resultsmentioning

confidence: 89%

Section: ■ Experimental Proceduresmentioning

confidence: 99%

Discovery and Single Crystal Growth of High Entropy Pyrochlores

et al. 2020

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“…In general, Ir metal clusters can easily form in a low O 2 pressure and at a high temperature, whereas high O 2 pressure favors the volatile IrO 3 phase [115], resulting in significant Ir loss during the growth. It is also worth noting that the Ir metallization and high volatility of IrO 3 have been common challenges in the PLD growth of many other iridates thin films [116][117][118][119][120][121][122], although the extent of the challenges appear dependent on the particular crystal structure and composition of the iridates. As a result, one must cooperatively tailor the O 2 pressure and substrate temperature to achieve stoichiometric films free of Ir metal impurities.…”

Section: Pulsed Laser Deposition (Pld) Of Iro 2 Thin Filmsmentioning

confidence: 99%

Recent progress on topological semimetal IrO₂: electronic structures, synthesis, and transport properties

Zhang,

Coughlin,

et al. 2024

J. Phys.: Condens. Matter

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5d transition metal oxides, such as iridates, have attracted significant interest in condensed matter physics throughout the past decade owing to their fascinating physical properties that arise from intrinsically strong spin-orbit coupling (SOC) and its interplay with other interactions of comparable energy scales. Among the rich family of iridates, iridium dioxide (IrO2), a simple binary compound long known as a promising catalyst for water splitting, has recently been demonstrated to possess novel topological states and exotic transport properties. The strong SOC and the nonsymmorphic symmetry that IrO2 possesses introduce symmetry-protected Dirac nodal lines (DNLs) within its band structure as well as a large spin Hall effect in the transport. Here, we review recent advances pertaining to the study of this unique SOC oxide, with an emphasis on the understanding of the topological electronic structures, syntheses of high crystalline quality nanostructures, and experimental measurements of its fundamental transport properties. In particular, the theoretical origin of the presence of the fourfold degenerate DNLs in band structure and its implications in the angle-resolved photoemission spectroscopy measurement and in the spin Hall effect are discussed. We further introduce a variety of synthesis techniques to achieve IrO2 nanostructures, such as epitaxial thin films and single crystalline nanowires, with the goal of understanding the roles that each key parameter plays in the growth process. Finally, we review the electrical, spin, and thermal transport studies. The transport properties under variable temperatures and magnetic fields reveal themselves to be uniquely sensitive and modifiable by strain, dimensionality (bulk, thin film, nanowire), quantum confinement, film texture, and disorder. The sensitivity, stemming from the competing energy scales of SOC, disorder, and other interactions, enables the creation of a variety of intriguing quantum states of matter.

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“…With the growth challenges described above, layer-by-layer growth of [111]-oriented pyrochlore iridate ultra-thin films has yet to be demonstrated. Nevertheless, significant advances in the fabrication of [111] A 2 Ir 2 O 7 thin films (A = Nd 112,113 , Eu 114,115 , Tb 116,117 , Pr [118][119][120] , Bi [121][122][123] ) and heterostructures 124 have been steadily demonstrated.…”

Section: [111] Pyrochlore Latticementioning

confidence: 99%

“…However, as no magnetic reflections associated with the AIAO order were detected by resonant scattering, Guo et al argued that the spontaneous magnetization is likely due to the localization of the Ir moments, which either creates additional spin chirality or strengthens the effective Pr-Pr coupling via the 4 f -5d interaction 119 . Additionally, linear magneto-resistance (MR) linked to the multiple types of charge carriers was found in [111] Bi 2 Ir 2 O 7 thin films, exhibiting striking resemblances to the scale invariant MR in the strange metal state of high Tc cuprates [121][122][123] .…”

Section: [111] Pyrochlore Latticementioning

confidence: 99%

Perspective: Strongly correlated and topological states in [111] grown transition metal oxide thin films and heterostructures

Chakhalian,

Liu,

Fiete

2020

Preprint

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We highlight recent advances in the theory, materials fabrication, and experimental characterization of strongly correlated and topological states in [111] oriented transition metal oxide thin films and heterostructures, which are notoriously difficult to realize compared to their [001] oriented counterparts. We focus on two classes of complex oxides, with the chemical formula ABO 3 and A 2 B 2 O 7 , where the B sites are occupied by an open-shell transition metal ion with a local moment, and the A sites are typically a rare earth. The [111] oriented quasi-two-dimensional lattices derived from these parent compound lattices can exhibit peculiar geometries and symmetries, namely, a buckled honeycomb lattice, as well as kagome and triangular lattices. These lattice motifs form the basis for emergent strongly correlated and topological states expressed in exotic magnetism, various forms of orbital ordering, topological insulators, topological semimetals, quantum anomalous Hall insulators, and quantum spin liquids. For transition metal ions with high atomic number, spin-orbit coupling plays a significant role and may give rise to additional topological features in the electronic band structure and in the spectrum of magnetic excitations. We conclude the Perspective by articulating open challenges and opportunities in this actively developing field.

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Stoichiometry control and electronic and transport properties of pyrochlore Bi2Ir2O7 thin films

Cited by 11 publications

References 64 publications

Discovery and Single Crystal Growth of High Entropy Pyrochlores

Discovery and Single Crystal Growth of High Entropy Pyrochlores

Recent progress on topological semimetal IrO₂: electronic structures, synthesis, and transport properties

Perspective: Strongly correlated and topological states in [111] grown transition metal oxide thin films and heterostructures

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Stoichiometry control and electronic and transport properties of pyrochlore Bi2Ir2O7 thin films

Cited by 11 publications

References 64 publications

Discovery and Single Crystal Growth of High Entropy Pyrochlores

Discovery and Single Crystal Growth of High Entropy Pyrochlores

Recent progress on topological semimetal IrO2: electronic structures, synthesis, and transport properties

Perspective: Strongly correlated and topological states in [111] grown transition metal oxide thin films and heterostructures

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Product

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Recent progress on topological semimetal IrO₂: electronic structures, synthesis, and transport properties