Speaker
Description
The metallic tetraboride TmB$_4$ is one of the best-known representatives of Shastry-Sutherland lattice (SSL), which is a two-dimensional geometrically frustrated lattice [1]. The long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange interaction between magnetic moments leads to antiferromagnetic (AF) ordering of dimers. Crystal field effect at Tm$^{3+}$ ion sites leads to strong Ising anisotropy along the $c$ axis, thus allowing the manifestation of the SSL in the $a$-$b$ plane, which is reflected by the fact that the magnetic field of saturation $H_{sat}$ along the $c$ axis is at least 10 times smaller than this in the perpendicular $a$-$b$ plane direction [2]. The magnetization $M$ along the $c$ axis exhibits the fractional magnetization plateaus (FMPs) with $M/M_{sat}$ = $1/11$, $1/9$, $1/8$ and $1/7$, where $M_{sat}$ is the saturation magnetization, in fields between $14$ kOe and $17.5$ kOe [1]. Half plateau with $M/M_{sat}=1/2$ arises between $17.5$ kOe and $36$ kOe. However, there is very little known about the development of FMPs, when the applied field $H$ deviates from $c$ axis and becomes parallel to $a$-$b$ plane. Up to now, there were only two $M(H)$ measurements for $H\perp c$ [2, 3], which show the saturation field of $H_{sat}\approx400$ kOe for $H \parallel [100]$ [2, 3] and different behavior of $M(H)$ with $H_{sat} > 550$ kOe for $H \parallel [110]$ [3], respectively. Within this work, we investigate the $M(H,\phi,T)$ angular development of FMPs in TmB$_4$ up to $600$ kOe (from $H \parallel c$ to $H \parallel [100]$ and from $H\parallel c$ to $H \parallel [110]$). The obtained results provide a new complex view on the FMPs in this material, which will allow the development of new (necessary) theoretical approaches of the metallic SSL.
Acknowledgements
This work was supported by projects APVV-23-0226, VEGA 2/0034/24, DAAD-SAS-2023-02. We acknowledge the support of the HLD-HZDR, member of the European Magnetic Field Laboratory (EMFL). M.O. acknowledges the support of the NextGenerationEU through the Recovery and Resilience Plan for Slovakia under the project No. 09I03-03-V04-00304.
References
[1] K. Siemensmeyer et al., “Fractional Magnetization Plateaus and Magnetic Order in the Shastry-Sutherland Magnet TmB$_4$”,Physical Review Letters, vol. 101, no. 17. American Physical Society (APS), Oct. 20, 2008. https://doi.org/10.1103/physrevlett.101.177201
[2] F. Iga et al., “Highly anisotropic magnetic phase diagram of a 2-dimensional orthogonal dimer system TmB4,” Journal of Magnetism and Magnetic Materials, vol. 310, no. 2. Elsevier BV, pp. e443–e445, Mar. 2007. https://doi.org/10.1016/j.jmmm.2006.10.476
[3] S. Yoshii et al., “High-field magnetization of TmB4,” Journal of Physics: Conference Series, vol. 51. IOP Publishing, pp. 59–62, Nov. 01, 2006. https://doi.org/10.1088/1742-6596/51/1/011
