Laser-Enhanced Single Crystal Growth of Non-Symmorphic Materials: Applications to an Eight-Fold Fermion Candidate

Abstract

Materials with nonsymmorphic symmetries have many applications and have recently come to the forefront as possibly harboring new topological states of matter, such as 8-fold fermions. Here, we report the single crystal growth of Bi 2 CuO 4 using the traveling solvent floating zone technique. Using laser heating combined with a 0.875 Bi 2 CuO 4 :0.125 Bi 2 O 3 solvent, we produce untwinned single crystal pieces. Three-dimensional X-ray microcomputed tomography is used to probe the fundamental origins of twinning, grain formation, and growth. Powder X-ray diffraction and Laue diffraction show that Bi 2 CuO 4 crystallizes in the space group P4/ncc (#130), orders antiferromagnetically with T N = 43 K, and, combined with comparisons to the literature, demonstrate the crystallinity and reproducibility of the synthesis. The entropy lost at the magnetic phase transition is ΔS mag = 0.25 ln(2); it arises from a high anisotropy in the magnetic interactions. We carry out a symmetry analysis demonstrating that Bi 2 CuO 4 's magnetic order implies a rich breaking of the parent 8-fold symmetric states. Our results provide a roadmap for the creation of future magnetic derivatives of 8-fold, double Dirac single crystals and related quantum states of matter with nonsymmorphic symmetries. This approach also offers guidance on improving the single growth of nonsymmorphic materials from cuprates to van der Waals solids.

Spin and Orbital Effects on Asymmetric Exchange Interaction in Polar Magnets: M(IO3)2 (M = Cu and Mn)

“…An anomaly in the C p / T vs T plot for α-Cu­(IO 3 ) 2 ( T N ≈ 7.2 K) and Mn­(IO 3 ) 2 ( T N ≈ 5.0 K) is observed at approximately the temperature of the magnetic phase transition to long-range AFM order of these materials as determined by magnetization and neutron diffraction experiments. This confirms that the transition observed in the C p / T vs T plot is magnetically driven. ,, The entropy recovered Δ S from the transition can be estimated from eq : where C v is the heat capacity at constant volume, which is approximated to be C p heat capacity at constant pressurefor solids at low temperatures, and T is the temperature. The phonon contribution to the magnetic specific heat and entropy can be estimated using an appropriate nonmagnetic isostructural material.…”

Thermal-field electron emission from three-dimensional Dirac and Weyl semimetals

“…For topological Dirac/Weyl semimetals, the quasiparticles around the Dirac point(s) are described by the effective Hamiltonian, H k = i,a v F i,a k i,a σ i where i = {x, y, z} and σ i is the Pauli matrix along î and the subscript a labels the ath Dirac cone [9,56,57,59,60]. The energy dispersion of these topological semimetals (SM) is…”

The Chemistry of Quantum Spin Liquids

“…The key for achieving a successful growth using the floating zone technique is to arrive at an appropriate combination of the principle growth parameters, such as feed rod quality, crystallization rate, growth atmosphere and gas pressure, temperature gradient profile and molten zone temperature and rotation rate. [67][68][69][70] This technique is therefore highly complex and requires an unparalleled amount of attention in order to ensure the isolation of high quality crystals, and failure to address any of the aforementioned parameters may result in defect-rich, sub-optimal samples.…”