Synthesis of a d1-titanium fluoride kagome lattice antiferromagnet

Abstract

S = 1 /2 kagome lattice antiferromagnets (KLAFs) have attracted great interest since they are closely associated with the long-sought quantum spin liquid (QSL) state. The realization of S = 1/2 KLAF remains an outstanding challenge and efforts have focused principally on Cu2+, d9 compounds. Herein, the synthesis of the first structurally perfect d1 KLAF, (CH3NH3)2NaTi3F12, is presented. The trivalent oxidation state and the Jahn-Teller distortion of Ti3+ ions are probed by single crystal X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis-NIR diffuse reflectance. No structural phase transitions can be observed from 1.8 K to 523 K. However, a glass transition can be observed due to the disordered, interlayer CH3NH3+ cations.The Curie-Weiss temperature, θcw= -139.5(7) K, and the lack of long-range ordering in magnetic susceptibility and specific heat imply that this compound is a QSL candidate. File list (2)download file view on ChemRxiv MA2NaTi3F12_Main-Text_CR.pdf (906.77 KiB) download file view on ChemRxiv MA2NaTi3F12_Supp_Info_CR.pdf (1.90 MiB)

Realizing square and diamond lattice S=1/2 Heisenberg antiferromagnet models in the α and β phases of the coordination framework, Abdeldaim1, Li2, Farrar3 et al. 2020Phys. Rev. Materials

“…Given its small amplitude and the porosity of the square network of α, we ascribe this feature to the freezing of the lattice water position. A similar feature has been observed in the specific heat data of (CH 3 NH 3 ) 2 NaTi 3 F 12 [56] and has been attributed to the ordering of the methylammonium groups. Above 50 K, χ m is well described by a modified Curie-Weiss (CW) law, χ…”

Synthesis of a d2 kagome lattice antiferromagnet, (CH3NH3)2NaV3F12

“…The structural features of these two compounds are listed in Table 1. 32 The q mp , which is the angle between the C-N bond of MA + (the MA + is composed of C1 and one of the nitrogen sites with C-N bond length of 1.44(3) A for 1-V and 1.42(2) A for 1-Ti) and (001) crystal plane in two compounds is 20.9(6) in 1-Ti and 23.8(6) in 1-V (demonstrated in Fig. S5 †).…”

“…S3 †) indicates that the disorder of MA + cations is static. 32 The dc magnetic susceptibility measurement of 1-V was performed from 1.8 K to 300 K under eld cooled (FC) and zero eld cooled (ZFC) conditions under 0.001 T (Fig. 2a).…”

“…24,31 However, the kagome lattices in these materials are distorted. Herein, building on our synthesis of the S ¼ 1/2 KLAF, (CH 3 NH 3 ) 2 NaTi 3 F 12 (1-Ti), 32 the analogous compound (CH 3 NH 3 ) 2 NaV 3 F 12 (1-V), an S ¼ 1 kagome lattice antiferromagnet, is reported.…”

Structural characterization and magnetic properties of chromium jarosite KCr3(OD)6(SO4)2

“…8 For example, herbertsmithite, ZnCu 3 (OH) 6 Cl 2 , has been extensively studied, but the intrinsic structural disorder (mixed Zn(II) (S = 0) and Cu(II) (S = 1/2) occupancy) disrupts the magnetic lattice. 9 Very recently, a novel Ti(III) kagomé compound, (CH 3 NH 3 ) 2 NaTi 3 F 12 , was reported, which shows no long-range magnetic order down to 0.1 K. 10 However, the interlayer CH 3 NH + 3 -ions are statistically disordered, which disrupts the local magnetic environment. 10 This demonstrates the general challenge of obtaining structurally non-disordered kagomé lattice systems.…”