Rebecca Dally1,Thuc Mai1,Kevin Garrity1,Michael Susner2,Benjamin Conner2,Amber McCreary1,Michael Mcguire3,Angela Hight Walker1,Nirmal Ghimire4,Lekhanath Poudel1,5,D.C. Jones4,Dina Michel4,Nishchal Thapa Magar4,Markus Bleuel1,5,Jidong Jiang6,John Mitchell6,Jeffrey Lynn1,Igor Mazin4
National Institute of Standards and Technology1,Air Force Research Laboratory2,Oak Ridge National Laboratory3,George Mason University4,University of Maryland5,Argonne National Laboratory6
Rebecca Dally1,Thuc Mai1,Kevin Garrity1,Michael Susner2,Benjamin Conner2,Amber McCreary1,Michael Mcguire3,Angela Hight Walker1,Nirmal Ghimire4,Lekhanath Poudel1,5,D.C. Jones4,Dina Michel4,Nishchal Thapa Magar4,Markus Bleuel1,5,Jidong Jiang6,John Mitchell6,Jeffrey Lynn1,Igor Mazin4
National Institute of Standards and Technology1,Air Force Research Laboratory2,Oak Ridge National Laboratory3,George Mason University4,University of Maryland5,Argonne National Laboratory6
Two-dimensional (2D) honeycomb and Kagome lattices have long been studied for the intriguing electronic and magnetic phenomena associated with these geometries. The <i>M</i>P<i>X</i><sub>3</sub> family (<i>M</i> = transition metal, <i>X</i> = S or Se) of magnetic van der Waals (vdW) materials features a transition metal honeycomb lattice where magnetism has already been observed in FePS<sub>3</sub>, NiPS<sub>3</sub>, CoPS<sub>3</sub>, and MnPSe<sub>3</sub> as the 2D limit is approached [1-3]. Theoretical studies [4,5] show that the bond-dependent Ising-type exchange for d<sup>7</sup> transition metals exists in a single layer of some van der Waals materials with a honeycomb lattice of Co, such as CoPS<sub>3</sub>. Here, we study the bulk properties of CoPS<sub>3</sub>, an antiferromagnet below 130 K, via temperature dependent magneto-Raman spectroscopy, magnetometry, calorimetric, and X-ray diffraction data. Magnetoelastic coupling is revealed which results in multiple complex local and bulk structural changes. This behavior is reminiscent to the case of bulk FePS<sub>3</sub>, where subtle structural changes occur below the Neel temperature.<br/><br/>For Kagome lattices, electronic flat bands, Dirac fermions, and quantum spin liquids have been the alluring features. More recently, the interplay between electronic and magnetic properties due to magnetic ions on the Kagome lattice sites has garnered attention as a way to manipulate topological electronic properties via the magnetism. The <i>R</i>Mn<sub>6</sub>Sn<sub>6</sub> (<i>R</i> = rare earth) family of compounds allows for these types of studies as they can host a wide range of elements at the <i>R</i> site, leading to a diverse collection of magnetic structures. Particularly, for <i>R</i> = Y, flat bands and Dirac points have been observed near the Fermi level [6], which contributes to the observed anomalous Hall effect. Further, the topological Hall effect (THE) was observed recently, where the underlying mechanism was found not to be due to static scalar spin chirality, but due to an imbalance of chiral magnons [7]. An important finding in our studies—via extensive bulk characterization in conjunction with theoretical and neutron diffraction work—is how the quasi-2D magnetic interactions with easy-plane anisotropy leads to the transverse conical magnetic structure phase which can host the THE.<br/> <br/>References<br/>[1] C.T. Kuo et al. <i>Sci. Rep</i>. <b>6, </b>20904 (2016).<br/>[2] Q. Zhang et al. <i>Nano Lett.</i> 21, <b>16</b>, 6938–6945 (2021).<br/>[3] Q. liu et al. <i>Phys. Rev. B</i> <b>103</b>, 235411 (2021).<br/>[4] R. Sano et al. <i>Phys. Rev. B</i> <b>97</b>, 014408 (2018).<br/>[5] H. Liu & G. Khaliullin, <i>Phys. Rev. B</i> <b>97</b>, 014407 (2018).<br/>[6] M. Li et al. <i>Nat. Commun. </i><b>12, </b>3129 (2021).<br/>[7] N. J. Ghimire et al. <i>Sci. Adv.</i> <b>6</b>, eabe2680 (2020).