The Two-Dimensional Square-Lattice S=1/2 Antiferromagnet Cu(pz)${}_2$(ClO${}_4$)${}_2$

Abstract

We present an experimental study of the two-dimensional S=1/2 square-lattice antiferromagnet Cu(pz)${}_2$(ClO${}_4$)${}_2$ (pz denotes pyrazine - $C_4{H}_4{N}_2$) using specific heat measurements, neutron diffraction and cold-neutron spectroscopy. The magnetic field dependence of the magnetic ordering temperature was determined from specific heat measurements for fields perpendicular and parallel to the square-lattice planes, showing identical field-temperature phase diagrams. This suggest that spin anisotropies in Cu(pz)${}_2$(ClO${}_4$)${}_2$ are small. The ordered antiferromagnetic structure is a collinear arrangement with the magnetic moments along either the crystallographic b- or c-axis. The estimated ordered magnetic moment at zero field is m_0=0.47(5)mu_B and thus much smaller than the available single-ion magnetic moment. This is evidence for strong quantum fluctuations in the ordered magnetic phase of Cu(pz)${}_2$(ClO${}_4$)${}_2$. Magnetic fields applied perpendicular to the square-lattice planes lead to an increase of the antiferromagnetically ordered moment to m_0=0.93(5)mu_B at mu_0H=13.5T - evidence that magnetic fields quench quantum fluctuations. Neutron spectroscopy reveals the presence of a gapped spin excitations at the antiferromagnetic zone center, and it can be explained with a slightly anisotropic nearest neighbor exchange coupling described by J_1^{xy}=1.563(13)meV and J_1^z=0.9979(2)J_1^{xy}.

References in corpus (4)

• Quantum dynamics and entanglement of spins on a square lattice
• Magnetic order in the S=1/2 two-dimensional molecular antiferromagnet, copper pyrazine perchlorate Cu(Pz)_2(ClO_4)_2
• Field-induced XY behavior in the S=1/2 antiferromagnet on the square lattice
• Effects of an external magnetic field on the gaps and quantum corrections in an ordered Heisenberg antiferromagnet with Dzyaloshinskii-Moriya anisotropy

Cited by in corpus (17)

• Spontaneous Magnon Decays
• Fractional excitations in the square-lattice quantum antiferromagnet
• Frustrated two dimensional quantum magnets
• Quasi-two-dimensional $S=1/2$ magnetism of Cu[C${}_6$H${}_2$(COO)${}_4$][C${}_2$H${}_5$NH${}_3$]${}_2$
• Square-lattice magnetism of diaboleite Pb2Cu(OH)4Cl2
• $J_1-J_2$ Square-Lattice Heisenberg Antiferromagnets with 4$d^1$ spins: AMoOPO${}_4$Cl (A = K, Rb)
• Physical properties of a quasi-two-dimensional square lattice antiferromagnet Ba${}_2$FeSi${}_2$O${}_7$
• Dynamical structure factor of quasi-2D antiferromagnet in high fields
• Magnetic properties of the S=1/2 quasi square lattice antiferromagnet CuF2(H2O)2(pyz) (pyz=pyrazine) investigated by neutron scattering
• Néel temperature and reentrant H-T phase diagram of quasi-2D frustrated magnets
• High-energy spin waves in the spin-1 square-lattice antiferromagnet La${}_2$NiO${}_4$
• $J_1$-$J_2$ square lattice antiferromagnetism in the orbitally quenched insulator MoOPO${}_4$
• Magnetism study on a frustration-free spatially anisotropic $S$ = 1 square lattice antiferromagnet Ni[SC(NH${}_2$)${}_2$]${}_6$Br${}_2$
• MoP${}_3$SiO${}_{11}$: a $4d^3$ honeycomb antiferromagnet with disconnected octahedra
• Low-temperature thermal conductivity and magnetic transitions of the kagomé-staircase compound Ni${}_3$V${}_2$O${}_8$
• Spin-flop transition accompanied with changing the type of magnetic ordering
• Extraordinary magnetic response of an anisotropic 2D antiferromagnet via site-dilution