Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session W60: Shastry-Sutherland and Quasi 1 D SystemsFocus
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Sponsoring Units: GMAG Chair: Lucas Pressley, Johns Hopkins University Room: Room 419 |
Thursday, March 9, 2023 3:00PM - 3:36PM |
W60.00001: Field-Induced Partial Disorder in a Shastry-Sutherland Lattice Invited Speaker: Madalynn Marshall Geometrical frustration in magnetic systems can drive the stabilization of exotic phases such as spin-liquids. The Shastry-Sutherland lattice is one such geometrically frustrated lattice that consists of a two-dimensional orthogonal arrangement of spin dimers and results in rich phase diagrams. In this talk I will present the findings of the possible field-induced spin liquid state of S=1 spin dimers in the Shastry-Sutherland lattice material BaNd2ZnS5. A metamagnetic transition in the bulk magnetization measurement was observed under field along the ab plane below TN = 2.9K. We established the Ising behavior in the Nd spins by the local magnetic susceptibility method with polarized neutrons at the paramagnetic state. The zero-field 2-Q antiferromagnetic order of ferromagnetic dimers was determined by neutrons at 1.4 K. The constituting propagation vectors q1 = (½ ½ 0) and q2 = (-½ ½ 0) each exhibit a “stripe” order when viewing multiple layers and a Néel-type arrangement in a single layer. By applying field along [1 -1 0] the two sublattices respond differently. The q1 magnetic sublattice remains relatively intact up to 6 T while the stripe phase of the q2 magnetic sublattice order is suppressed at the critical field Hc = 1.7 T, indicating an emerging partial disorder, liquid state of ferromagnetic dimers, corresponding to the metamagnetic transition in the bulk measurement. With this information we constructed an H-T phase diagram from the bulk magnetization measurements that clearly defines the “stripe” state at lower field and a field polarized state at upper fields with a critical region emerging in between represented as a spin dimer liquid phase. |
Thursday, March 9, 2023 3:36PM - 3:48PM |
W60.00002: Single crystal synthesis and physical properties of a Shastry-Sutherland compound, BaNd2ZnS5 Brianna Billingsley, Huibo Cao, Madalynn Marshall, Zhixue Shu, Tai Kong Shastry-Sutherland (SS) lattice is a classical geometrically frustrated lattice type featuring a competition between nearest neighbor and next nearest neighbor interactions. In this talk, we present our recent work on a high-purity, single-crystalline semiconductor BaNd2ZnS5 where Nd atoms form a two-dimensional SS lattice [1]. Crystal synthesis procedure and detailed physical property characterizations via x-ray diffraction, magnetization and heat capacity measurements will be presented. BaNd2ZnS5 orders antiferromagnetically at 2.9 K with a Kramer’s doublet CEF ground state. Nd magnetic moments align primarily within the ab-plane, and magnetic isothermal measurements show metamagnetic transitions at ~15 kOe for [110] and ~21 kOe for [100]. Magnetic properties of other rare earth members in this family of compounds will also be discussed. |
Thursday, March 9, 2023 3:48PM - 4:00PM |
W60.00003: Magnetic and Neutron Studies of New Yb- and Nd-based Shastry-Sutherland Compounds Matthew Ennis, Rabindranath Bag, Lalit Yadav, Clarina dela Cruz, Alexander I Kolesnikov, David E Graf, Sara Haravifard In the study of frustrated magnetism, the Shastry-Sutherland lattice (SSL), an arrangement of orthogonal dimers with competing interactions J and J' between and within the dimers, represents one of the few exactly solvable structures. The SSL ground state is known when the ratio J'/J is small and large, but the states of the intermediate values are still unclear. We have recently begun synthesis and characterization of a new family of rare-earth based SSL compounds. We have successfully grown large single crystals using the optical floating zone technique and have performed magnetic and thermal characterization measurements. We have also performed neutron scattering measurements on these samples. In this talk we will present our recent experimental efforts obtained for the Yb- and Nd-based compounds belonging to this new SSL system. |
Thursday, March 9, 2023 4:00PM - 4:12PM |
W60.00004: Neutron scattering and thermodynamics studies of new Tb and Er based Shastry Sutherland Lattice compound. Lalit Yadav, Rabindranath Bag, Matthew Ennis, Clarina dela Cruz, Songxue Chi, Alexander I Kolesnikov, Adam A Aczel, Eun Sang Choi, David E Graf, Sara Haravifard In two -dimensional magnetic compounds, the Shastry-Sutherland lattice (SSL), an orthogonal arrangement of dimers with antiferromagnetic interdimer coupling J′ and the intradimer coupling J, have attracted attention due to their complex phase diagrams, displaying a variety of magnetic phases in magnetic fields and pressure; such as dimer state, plaquette state, fractional magnetization plateaus, and crystals of bound states. We have synthesized single crystals of a new family of Tb and Er-based SSL compounds and characterized them using thermal, magnetic, and neutron scattering measurements. In this talk, we are going to present our results for these compounds. |
Thursday, March 9, 2023 4:12PM - 4:24PM |
W60.00005: Theory of absorption in the frustrated spin gap system SrCu2(BO3)2 Shin Miyahara In magnetoelectric mulitferroics, there are strong couplings between magnetization and electric polarization, which induces magnetoelectric effects. Moreover, such magnetoelectric couplings induce anomalous behaviors even in dynamical processes. It is well known that an electromagnon, i.e., an electro active magnon, process arises in the cycloidal magnets. We show that electromagnetic couplings can exist even in spin gap systems and induce anomalous spin excitations. As a typical example, we discuss the absorption process in the frustrated two-dimensional spin gap system SrCu2(BO3)2. SrCu2(BO3)2 is a realization of the Shastry-Sutherland model of which the ground state is exactly described as a direct product of dimer singlet states. Spin excitation spectra have been investigated by ESR and IR and spin gap and bound states of two triplets excitations are observed. However, the origin and mechanism of the observation are still mysetry. We show that the spin gap excitation and the bound states of two triplets are active due to the electric components of light in the dimer singlets phase in the Shastry-Sutherland material SrCu2(BO3)2. |
Thursday, March 9, 2023 4:24PM - 4:36PM |
W60.00006: Magnetoelastic interactions in SrCu2(BO3)2 studied by first principles calculations and Raman experiments at high magnetic fields William K Peria, Komalavalli Thirunavukkuarasu, Guillaume Radtke, Zhengguang Lu, Michele Lazzeri, Peter Christianen, Victor Correa, Hanna A Dabkowska, Bruce D Gaulin, Dmitry Smirnov, Marcelo Jaime, Andres Saul SrCu2(BO3)2 is both a Mott-Hubbard insulator and well-known physical realization of the Shastry-Sutherland model [1]. This compound is rich in magnetic phases and textures, due in large part to the strong geometric frustration of the magnetic Cu2+-Cu2+ dimers. A signature of this compound is the existence of magnetization plateaus at low temperatures, which have been probed with both dilatometry [2] and measurements of the magnetocaloric effect [2–3]. Here we present measurements of the dynamic and static crystal lattice properties of SrCu2(BO3)2 using Raman scattering, magnetostriction, and thermal expansion measurements at magnetic fields of up to 45 T. The Raman-active “pantograph modes”—previously shown to be a major cause of the strong spin-lattice coupling in SrCu2(BO3)2 [4]—show anomalous hardening with increasing magnetic field and temperature, and are likely responsible for stabilizing the high field magnetization plateaus. Dilatometry measurements are used to correlate the field-dependent Raman modes with the closing of the spin gap, as well as fractional-magnetization stripe states M = 1/4 Ms and M = 1/3 Ms, where Ms is the saturation magnetization. |
Thursday, March 9, 2023 4:36PM - 4:48PM |
W60.00007: Magnetization of the Exact Ground State of the Maple-leaf Model Pratyay Ghosh, Tobias Müller, Jannis Seufert, Frederic Mila, Ronny Thomale The quantum antiferromagnet on the maple-leaf lattice realizes an exact dimer ground state with coupling anisotropy for one of the three inequivalent nearest-neighbor bonds. Together with the Shastry-Sutherland Hamiltonian, this is the only other model with an exact dimer ground state for all two-dimensional lattices with uniform tilings. We present its response to an external magnetic field. Performing a strong-coupling expansion, we arrive at an effective bosonic Hamiltonian for the magnetic particle interactions, which allows us to predict several novel magnetization plateaus. We also describe how the structure of the lattice affects the dynamical behavior of these magnetic excitations, leading to the condensation of multi-particle bound states and the emergence of very low magnetizations. |
Thursday, March 9, 2023 4:48PM - 5:00PM |
W60.00008: Frustrated magnetic correlations in Cairo lattice material Yu Li, Daniel Phelan, Xinglong Chen, Hong Zheng, Feng Ye, Stephan Rosenkranz, Arthur P Ramirez Geometric frustration in magnetic materials can occur in structures based on polygons that contain an odd number of antiferromagnetically interacting atoms on the vertices. The Cairo lattice is one such structure built upon frustrated pentagons, which might induce interesting physics different from triangle-based lattices[1]. Here, we report our recent diffuse neutron scattering study on a prototype Cairo pentagonal lattice material Bi2Fe4O9[2] with Ga substitution. Combining with computational simulation and advanced 3D-mΔpdf analysis, we show that there exist two types of short-range magnetic orders buried in a previously thought single spin glass state in Bi2Fe4-xGaxO9 with Ga substitution. These are distinct from the non-collinear magnetic order in the undoped compound Bi2Fe4O9. Our results indicate a high tunability of magnetic correlations on the frustrated Cairo lattice. We compare the results from different simulations and analysis methods, and this comparison testifies to their suitability and robustness in solving short-range correlations in complex/disordered materials. |
Thursday, March 9, 2023 5:00PM - 5:12PM |
W60.00009: Critical dielectric relaxation at a magnetic quantum phase transition Daniel Flavian Blasco, Shohei Hayashida, Pavel Volkov, Kirill Povarov, Zewu Yan, Severian Gvasaliya, Premala Chandra, Andrey Zheludev Slow relaxational dynamics of electric polarization is characteristic of ferroelectrics and reveals itself in dissipative anomalies of the dielectric constant. We report the observation of such anomalies in a nonpolar frustrated quasi-1D quantum ferro-antiferromagnet Cs2Cu2Mo3O12. The dielectric response shows two components: a critical divergence at the field-induced magnetic quantum critical point (QCP), and an unusual dissipative peak at ultra-low temperatures, present at all fields. The former has been also identified in a sister compound and stems from the inverse Dzyaloshinskii-Moriya mechanism in the strongly magnetized state. The latter manifests itself as a strong modulation in the complex permittivity with a marked field and temperature dependence, which also becomes critical at the magnetic transition. Analysis using a Cole-Cole relaxation model indicates that the dynamics is mediated by the soft magnon that softens at the QCP. These observations demonstrate the emergence of dynamical electric dipole moments in a frustrated spin system. |
Thursday, March 9, 2023 5:12PM - 5:24PM |
W60.00010: Hydrodynamic theory of spinon spin current. Oleg A Starykh, Anna Keselman, Ren-Bo Wang, Leon Balents Fractionalized quasi-particles of the Heisenberg spin-1/2 chain have been extensively probed by inelastic neutron scattering, electron spin, and nuclear magnetic resonances and other dynamical probes in the past. Here we present a theoretical analysis of the spinon spin current between the Heisenberg spin-1/2 chain and nonmagnetic conductor in the presence of the external magnetic field. We find that the residual backscattering interaction between spinons controls the low-temperature spinon current. Specifically, the current vanishes when the spin chain is tuned, by varying exchange interaction between the next-nearest spins, to the non-interacting spinon point. Our approximate analytical calculations are well supported by numerical results based on matrix-product-state techniques. |
Thursday, March 9, 2023 5:24PM - 5:36PM |
W60.00011: Quantum order-from-disorder in frustrated spin nanotubes Zekun Zhuang We investigate purely quantum order-from-disorder in a frustrated spin nanotube, described by a J1-J2 Heisenberg model wrapped around a cylinder. Using Schwinger boson theory and Density Matrix Renormalization Group (DMRG), we compute the ground-state phase diagram, revealing a Z2 phase in which the collinear spin stripes form either a right or left handed helix around the nanotube. We derive an analytic estimate for the critical ηc=J1/2J2 where the Z2 phase transition occurs which is in agreement with the DMRG results. |
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