Modulated crystal structure of the atypical charge density wave state of single-crystal 
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Ramakrishnan, S.; Schönleber, Andreas; Bao, Jin‐Ke; Rekis, Toms; Kotla, Surya Rohith; Schaller, Achim M.; Smaalen, Sander van; Noohinejad, Leila; Tolkiehn, Martin; Paulmann, Carsten; Sangeetha, N. S.; Pal, D.; Thamizhavel, A.; Ramakrishnan, S.

doi:10.1103/physrevb.104.054116

Cited by 11 publications

(14 citation statements)

References 42 publications

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“…Just as in the case of R 2 Ir 3 Si 5 ( R = Lu, Er), , we observe that the electrical resistivity exhibits a T 2 dependence below T = 50 K, which is up to much higher temperatures than ∼10 K to be associated with Fermi-liquid behavior, implying dominant contributions from short-range magnetic fluctuations of Ho spins in the absence of long-range magnetic ordering.…”

Section: Resultssupporting

confidence: 70%

“…Analysis of the modulation amplitudes and distances revealed that Ho 2 Ir 3 Si 5 follows a similar pattern as R 2 Ir 3 Si 5 ( R = Lu, Er), , such that the CDW resides on zigzag chains of Ir1a–Ir1b atoms, as they have the shortest metal–metal distances and exhibit the largest modulation of these distances (Figure ). The lattice distortion results in alternating short and long Ir1a–Ir1b distances, where the shorter distance is the most affected by the modulation.…”

Section: Resultsmentioning

confidence: 91%

“…Investigations of the CDW in Lu 2 Ir 3 Si 5 have been extensively done. − Studies by transmission electron microscopy (TEM) reported the modulation wave vector as q = with σ = 0.23–0.25 around 200 K . Recently, the modulated crystal structure of Lu 2 Ir 3 Si 5 was reported as similar to that of Er 2 Ir 3 Si 5 . In both systems it was elucidated that the CDW resides on the zigzag chains of Ir atoms along c .…”

Section: Introductionmentioning

confidence: 91%

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Coupling between Charge Density Wave Ordering and Magnetism in Ho₂Ir₃Si₅

et al. 2023

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Ho 2 Ir 3 Si 5 belongs to the family of three-dimensional (3D) R 2 Ir 3 Si 5 (R = Lu, Er, Ho) compounds that exhibit a first-order, charge-density-wave (CDW) phase transition, where there is a strong orthorhombic-to-triclinic distortion of the lattice accompanied by superlattice reflections. The analysis by single-crystal X-ray diffraction (SXRD) has revealed that the Ir−Ir zigzag chains along c are responsible for the CDW in all three compounds. The replacement of the rare earth element from nonmagnetic Lu to magnetic Er or Ho lowers T CDW , where T CDWLu = 200 K, T CDWEr = 150 K, and T CDWHo = 90 K. Out of the three compounds, Ho 2 Ir 3 Si 5 is the only system where second-order superlattice reflections could be observed, indicative of an anharmonic shape of the modulation wave. The CDW transition is observed as anomalies in the temperature dependencies of the specific heat, electrical conductivity, and magnetic susceptibility, which includes a large hysteresis of 90 to 130 K for all measured properties, thus corroborating the SXRD measurements. Similar to previously reported Er 2 Ir 3 Si 5 , there appears to be a coupling between CDW and magnetism such that the Ho 3+ magnetic moments are influenced by the CDW transition, even in the paramagnetic state. Moreover, earlier investigations on polycrystalline material revealed antiferromagnetic (AFM) ordering at T N = 5.1 K, whereas AFM order is suppressed and only the CDW is present down to at least 0.1 K in our highly ordered single crystal. First-principles calculations predict Ho 2 Ir 3 Si 5 to be a metal with coexisting electron and hole pockets at the Fermi level. The Ho and Ir atoms have spherically symmetric metallic-type charge density distributions that are prone to CDW distortion. Phonon calculations affirm that the Ir atoms are primarily responsible for the CDW distortion, which is in agreement with the experiment.

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Section: Resultssupporting

confidence: 70%

Section: Resultsmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 91%

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Coupling between Charge Density Wave Ordering and Magnetism in Ho₂Ir₃Si₅

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“…This behaviour is in contrast to other CDW materials, like Er 2 Ir 3 Si 5 , Lu 2 Ir 3 Si 5 and BaFe 2 Al 9 , for which the CDW transitions are accompanied by large lattice distortions (Ramakrishnan et al, 2020(Ramakrishnan et al, , 2021Meier et al, 2021).…”

Section: Introductioncontrasting

confidence: 69%

Orthorhombic charge density wave on the tetragonal lattice of EuAl₄

Ramakrishnan

Kotla

Rekis

et al. 2022

Int Union Crystallogr J

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EuAl4 possesses the BaAl4 crystal structure type with tetragonal symmetry I4/mmm. It undergoes a charge density wave (CDW) transition at T CDW = 145 K and features four consecutive antiferromagnetic phase transitions below 16 K. Here we use single-crystal X-ray diffraction to determine the incommensurately modulated crystal structure of EuAl4 in its CDW state. The CDW is shown to be incommensurate with modulation wave vector q = (0,0,0.1781 (3)) at 70 K. The symmetry of the incommensurately modulated crystal structure is orthorhombic with superspace group Fmmm(00σ)s00, where Fmmm is a subgroup of I4/mmm of index 2. Both the lattice and the atomic coordinates of the basic structure remain tetragonal. Symmetry breaking is entirely due to the modulation wave, where atoms Eu and Al1 have displacements exclusively along a, while the fourfold rotation would require equal displacement amplitudes along a and b. The calculated band structure of the basic structure and interatomic distances in the modulated crystal structure both indicate the Al atoms as the location of the CDW. The temperature dependence of the specific heat reveals an anomaly at T CDW = 145 K of a magnitude similar to canonical CDW systems. The present discovery of orthorhombic symmetry for the CDW state of EuAl4 leads to the suggestion of monoclinic instead of orthorhombic symmetry for the third AFM state.

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“…This feature might explain why the lowering of symmetry has not been found in earlier studies on EuAl 4 . This behavior is in contrast to other CDW materials, like Er 2 Ir 3 Si 5 , Lu 2 Ir 3 Si 5 and BaFe 2 Al 9 , for which the CDW transitions are accompanied by large lattice distortions (Ramakrishnan et al, 2020;Ramakrishnan et al, 2021;Meier et al, 2021) The phenomenon of CDW was originally identified as a property of crystals with quasi-one-dimensional (1D) electron bands, such as NbSe 3 and K 0.3 MoO 3 (Gruner, 1994;Monceau, 2012). A CDW is formed due to Fermi surface nesting (FSN), where the nesting vector of the periodic structure becomes the wave vector of the CDW of the metallic bands as well as of the accompanying modulation of the atomic positions (periodic lattice distortion-PLD).…”

Section: Introductionmentioning

confidence: 65%

Orthorhombic charge density wave on the tetragonal lattice of EuAl4

Ramakrishnan,

Kotla,

Rekis

et al. 2022

Preprint

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PREPRINT: IUCrJ A Journal of the International Union of Crystallography EuAl 4 possesses the BaAl 4 crystal structure type with tetragonal symmetry I4/mmm. It undergoes a charge-density-wave (CDW) transition at T CDW = 145 K and it features four consecutive antiferromagnetic phase transitions below 16 K. Here, we use single-crystal x-ray diffraction to determine incommensurately modulated crystal structure of EuAl 4 in its CDW state. The CDW is shown to be incommensurate with modulation wave vector q = (0, 0, 0.1781(3)) at 70 K. The symmetry of the incommensurately modulated crystal structure is orthorhombic with superspace group F mmm(00σ)s00, where F mmm is a subgroup of I4/mmm of index 2. Both the lattice and the atomic coordinates of the basic structure remain tetragonal. Symmetry breaking is entirely due to the modulation wave, where atoms Eu and Al1 have displacements exclusively along a, while the fourfold rotation would require equal displacement amplitudes along a and b. The calculated band structure of the basic structure and interatomic distances in the modulated crystal structure both indicate the aluminum atoms as location of the CDW. The temperature dependence of the specific heat reveals an anomaly at T CDW = 145 K of a magnitude similar to canonical CDW systems. The present discovery of orthorhombic symmetry for the CDW state of EuAl 4 leads to the suggestion of monoclinic instead of orthorhombic symmetry for the third AFM state.

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Modulated crystal structure of the atypical charge density wave state of single-crystal Lu2Ir3Si5

Cited by 11 publications

References 42 publications

Coupling between Charge Density Wave Ordering and Magnetism in Ho₂Ir₃Si₅

Coupling between Charge Density Wave Ordering and Magnetism in Ho₂Ir₃Si₅

Orthorhombic charge density wave on the tetragonal lattice of EuAl₄

Orthorhombic charge density wave on the tetragonal lattice of EuAl4

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Modulated crystal structure of the atypical charge density wave state of single-crystal Lu2Ir3Si5

Cited by 11 publications

References 42 publications

Coupling between Charge Density Wave Ordering and Magnetism in Ho2Ir3Si5

Coupling between Charge Density Wave Ordering and Magnetism in Ho2Ir3Si5

Orthorhombic charge density wave on the tetragonal lattice of EuAl4

Orthorhombic charge density wave on the tetragonal lattice of EuAl4

Contact Info

Product

Resources

About

Coupling between Charge Density Wave Ordering and Magnetism in Ho₂Ir₃Si₅

Coupling between Charge Density Wave Ordering and Magnetism in Ho₂Ir₃Si₅

Orthorhombic charge density wave on the tetragonal lattice of EuAl₄