Spontaneous structural distortion of the metallic Shastry-Sutherland system 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Dy</mml:mi><mml:msub><mml:mi mathvariant="normal">B</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>
 by quadrupole-spin-lattice coupling

Sim, Hasung; Lee, Seongsu; Hong, Kwangpyo; Jeong, Jaehong; Zhang, J. R.; Kamiyama, Takashi; Adroja, D. T.; Murray, Claire; Thompson, Stephen P.; Iga, Fumitoshi; Ji, S.; Khomskii, D. I.; Park, Je‐Geun

doi:10.1103/physrevb.94.195128

Cited by 10 publications

(8 citation statements)

References 23 publications

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“…However, the types of their orderings in DyB4 are distinct from the ones in HoB4. At T = TN1, collinear antiferromagnetic ordering is developed along the c-axis, while quadrupolar ordering is developed at T = TN2, which accompanies the structural distortion and magnetic order in both the ab-plane and the c-axis [28].…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, the lattice structure formed by R ions in the c plane is the Shastry-Sutherland lattice (SSL), which is a geometrically frustrated system, exhibiting double magnetic transitions, magnetic dipole ordering at T = TN1 and quadrupolar ordering at T = TN2 [19]. Since the 1970s, the physical properties and magnetic structure of RB4 compounds have been studied [20][21][22][23][24] and, recently, the detailed ground state of RB4 (R = Dy, Ho) was re-investigated by resonant X-ray scattering and X-ray and neutron diffraction [17, [25][26][27][28]. The two successive magnetic transitions of these compounds are related to the collinear antiferromagnetic transition at T = TN1 along the c-axis, the quadrupolar ordering at T = TN2 and the strong quadrupolar fluctuation between them.…”

Section: Introductionmentioning

confidence: 99%

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Quadrupolar ordering and exotic magnetocaloric effect in RB4 (R = Dy, Ho)

Song

Cho

Kang

et al. 2020

Sci Rep

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The interplay of charge, spin, orbital and lattice degrees of freedom has recently received great interest due to its potential to improve the magnetocaloric effect (MCE) for the purpose of magnetic cooling applications. Here we propose a new mechanism for a giant inverse MCE in rare-earth tetraborides, especially for Ho1-xDyxB4 (x = 0.0, 0.5, and 1.0). For x = 0.0, 0.5, and 1.0, the maximum entropy changes of the giant inverse MCE are found to be 22.7 J/kg⋅K, 19.6 J/kg⋅K, and 19.0 J/kg⋅K with critical fields of ≈ 25 kOe, 40 kOe, and 50 kOe, respectively. It is remarkable that such a giant MCE is realized, even when applying a low magnetic field, which enables a field-tuned entropy change and brings about a significant advantage for several applications. For all compounds, we have systematically studied how the entropy changes as a function of the field and temperature and investigated their correlation with consecutive double transitions, i.e., the magnetic dipolar order at T = TN and the quadrupolar order at T = TQ (TQ < TN). We found that the maximum entropy change occurs at T = TQ and the critical field associated with the meta-magnetic transition, which is in good agreement with the experimental data.Thus, we elucidate that this unique behaviour is attributed to the strong coupling between magnetic dipoles and quadrupoles in the presence of strong spin-orbit coupling and geometric frustration. Our work offers new insights into both the academic interest of multipolar degrees of freedom in magnetic materials and the discovery of giant MCE with various applications for magnetic cooling systems. I. INTRODUCTIONThe magnetocaloric effect (MCE) is a thermodynamic property, in which heating or cooling occurs in magnetic materials when applying a magnetic field. For the conventional MCE, the cooling mechanism is based on the adiabatic demagnetization process. In contrast, the inverse situation can also occur, where the system is cooled via adiabatic magnetization. This is often termed as the inverse MCE.Refrigeration based on the conventional or inverse MCE is a solid-state cooling application, which is energy efficient, noise-free, and environmentally friendly. Thus, a large MCE is attractive as an alternative to conventional vapor refrigeration [1]. In particular, a large MCE in a low-temperature region is being actively studied for the purpose of gas liquefaction (hydrogen and helium), space technology, and diverse scientific research technologies. Although various methods have been devised for the development of novel solid-state cooling, the design and discovery of new materials that exhibit a large MCE are still important.Intuitively, a large MCE is expected in materials with a first order magnetic phase transition accompanied with a spontaneous magnetization jump. However, this gives rise to heat loss during the refrigeration cycle due to the hysteresis, irreversibility and the narrow working temperature range. As another promising candidate, a system with geometrical frustration may contain an enormous groun...

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quadrupolar ordering and exotic magnetocaloric effect in RB4 (R = Dy, Ho)

Song

Cho

Kang

et al. 2020

Sci Rep

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“…The paramagnetic parent phase of DyB 4 has space group 127 P4/ mbm. In experiments 56 , this material was reported to have two competing spin configurations that correspond to the Γ 2 (with MSG 127.395 P4=m 0 b 0 m 0 ) and Γ 4 (with MSG 127.392 P4 0 =m 0 b 0 m) magnetic states, as shown in Fig. 3b, c.…”

Section: Dirac Fermions and Magnetic Wallpaper Groupsmentioning

confidence: 92%

“…3b, c. Between them, the Γ 2 state was reported to be more favored 56 . Note that the Γ 4 phase can support a Type-III TMDI with (001)-surface MWG P4 0 g 0 m. Here, we investigate the conditions in which the Γ 4 state becomes the magnetic ground state in DyB 4 based on DFT+U(where U is the onsite Coulomb interaction) calculations.…”

Section: Dirac Fermions and Magnetic Wallpaper Groupsmentioning

confidence: 99%

Magnetic wallpaper Dirac fermions and topological magnetic Dirac insulators

et al. 2023

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Topological crystalline insulators (TCIs) can host anomalous surface states which inherits the characteristics of crystalline symmetry that protects the bulk topology. Especially, the diversity of magnetic crystalline symmetries indicates the potential for novel magnetic TCIs with distinct surface characteristics. Here, we propose a topological magnetic Dirac insulator (TMDI), whose two-dimensional surface hosts fourfold-degenerate Dirac fermions protected by either the $${p}_{c}^{{\prime} }4mm$$ p c ′ 4 m m or $$p{4}^{{\prime} }{g}^{{\prime} }m$$ p 4 ′ g ′ m magnetic wallpaper group. The bulk topology of TMDIs is protected by diagonal mirror symmetries, which give chiral dispersion of surface Dirac fermions and mirror-protected hinge modes. We propose candidate materials for TMDIs including Nd4Te8Cl4O20 and DyB4 based on first-principles calculations, and construct a general scheme for searching TMDIs using the space group of paramagnetic parent states. Our theoretical discovery of TMDIs will facilitate future research on magnetic TCIs and illustrate a distinct way to achieve anomalous surface states in magnetic crystals.

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“…Here, a natural starting point is to first look for realizations of the Shastry-Sutherland lattice in spin-orbit dominated materials. One step in this direction has been taken by exploring the 4f material DyB 4 [35][36][37][38], for which the spin-orbit coupling -enhanced by the relatively high atomic number of Z = 66 for Dy (compared to Z = 44/77 for the Ru-/Ir-based Kitaev materials) -holds promise to give rise to the required bond-directional exchange interactions. Given a suitable candidate material, the experimental detection of the corner modes of a second-order Kitaev spin liquid still poses a number of challenges.…”

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confidence: 99%

Majorana corner modes in a second-order Kitaev spin liquid

et al. 2018

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Higher-order topological insulators are distinguished by the existence of topologically protected modes with codimension two or higher. Here, we report the manifestation of a second-order topological insulator in a two dimensional frustrated quantum magnet, which exhibits topological corner modes. Our exactly-solvable model is a generalization of the Kitaev honeycomb model to the Shastry-Sutherland lattice that, besides a chiral spin liquid phase, exhibits a gapped spin liquid with Majorana corner modes, which are protected by two mirror symmetries. This second-order Kitaev spin liquid remains stable in the presence of thermal fluctuations and undergoes a finite-temperature phase transition evidenced in large-scale quantum Monte Carlo simulations.

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Spontaneous structural distortion of the metallic Shastry-Sutherland system DyB4 by quadrupole-spin-lattice coupling

Cited by 10 publications

References 23 publications

Quadrupolar ordering and exotic magnetocaloric effect in RB4 (R = Dy, Ho)

Quadrupolar ordering and exotic magnetocaloric effect in RB4 (R = Dy, Ho)

Magnetic wallpaper Dirac fermions and topological magnetic Dirac insulators

Majorana corner modes in a second-order Kitaev spin liquid

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