Quasi-two-dimensional magnetism in spin-½ square lattice compound Cu[C6H2(COO)4][H3N-(CH2)2-NH3]·3H2O

S. Guchhait; S. Baby; M. Padmanabhan; A. Medhi; R. Nath

doi:10.1209/0295-5075/133/57006

All issues

Volume 133 / No 5 (March 2021)

EPL, 133 5 (2021) 57006

Abstract

Issue		EPL Volume 133, Number 5, March 2021


Article Number		57006
Number of page(s)		7
Section		Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI		https://doi.org/10.1209/0295-5075/133/57006
Published online		29 April 2021

EPL, 133 (2021) 57006

Quasi-two-dimensional magnetism in spin-½ square lattice compound Cu[C₆H₂(COO)₄][H₃N-(CH₂)₂-NH₃]·3H₂O

S. Guchhait¹, S. Baby², M. Padmanabhan³, A. Medhi¹ and R. Nath¹^(a)

¹ School of Physics, Indian Institute of Science Education and Research - Thiruvananthapuram-695551, Kerala, India
² Department of Chemistry, Christian College - Chengannur, Alappuzha, Kerala-689122, India
³ Department of Chemistry, Amrita Vishwa Vidyapeetham - Amritapuri, Kerala-690525, India

^(a) rnath@iisertvm.ac.in

Received: 27 November 2020
Accepted: 9 February 2021

Abstract

We report the crystal growth and structural and magnetic properties of quasi-two-dimensional $S=1/2$ quantum magnet Cu[C₆H₂(COO)₄][H₃N-(CH₂)₂-NH₃]·3H₂O. It is found to crystallize in a monoclinic structure with space group $C2/m$ . The CuO₄ plaquettes are connected into a two-dimensional framework in the ab-plane through the anions of [C₆H₂(COO)₄]⁴⁻ (pyromellitic acid). The [H₃N-(CH₂)₂-NH₃] $^{2+}{}\cdot{}$ 3H₂O groups are located between the layers and provide a weak interlayer connection via hydrogen (H...O) bonds. The temperature-dependent magnetic susceptibility is well described by $S=1/2$ frustrated square lattice $(J_1-J_2)$ model with nearest-neighbor interaction $J_1/k_{\text B} \simeq 5.37\ \text{K}$ and next-nearest-neighbor interaction $J_2/k_{\text B} \simeq -0.37\ \text{K}$ . Our analysis using frustrated rectangular lattice $(J_{1a,b}-J_2)$ model also confirms almost isotropic nearest-neighbour interactions ( $J_{1{\text a}}/k_{\text B} \simeq 5.31\ \text{K}$ and $J_{1{\text b}}/k_{\text B} \simeq 5.38\ \text{K}$ ) in the ab-plane and $J_2/k_{\text B}\simeq-0.24\ \text{K}$ . Further, the isothermal magnetization at $T=1.9\ \text{K}$ is also well described by a non-frustrated square lattice model with $J_1/k_{\text B} \simeq 5.2\ \text{K}$ . Based on the $J_2/J_1$ ratio, the compound can be placed in the Néel antiferromagnetic state of the $J_1 - J_2$ phase diagram. No signature of magnetic long-range order is detected down to 2 K.

PACS: 75.50.Ee – Antiferromagnetics / 75.10.Jm – Quantized spin models, including quantum spin frustration / 75.30.Et – Exchange and superexchange interactions

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