Multiple Metamagnetic Transitions in Antiferromagnet Yb₂Pt₂Pb with the Shastry–Sutherland Lattice

Abstract

From the magnetization and magnetoresistance measurements, we constructed the magnetic phase diagram of Yb 2 Pt 2 Pb with the Shastry-Sutherland lattice, which consists of characteristic two phases below 1 K with many metamagnetic transitions, revealing magnetic frustrations.

Magnetic structure ofYb2Pt2Pb: Ising moments on the Shastry-Sutherland lattice

“…From a wholly experimental perspective, the presence of two antiferromagnetic domains would likely also lead to significant hysteresis in the temperature dependencies of the low field magnetic susceptibility when the sample is cooled into the antiferromagnetic state in either zero field [zero field cooled (ZFC)] or in a field that is larger than 3 T [field cooled (FC)], the saturation field. Our measurements find no evidence for hysteresis in the ZFC or FC susceptibilities χ (T ), or in the field dependence of the magnetization M(B), other than near the quantized magnetization steps [18][19][20].…”

“…In metallic Yb 2 Pt 2 Pb, Yb moments form the orthogonal dimers of the SSL planes, and AF order appears below the Néel temperature T N = 2.07 K [17]. The exchange interactions J 5 K and J /J 1 deduced from the magnetic susceptibility χ (T ) [18] are much smaller in Yb 2 Pt 2 Pb than in the RB 4 , and a field of only 1.23 T, applied along the (110) or (−110) dimer bond directions, partially suppresses the B = 0 AF order, accompanied by quantized M(B) steps [18][19][20] that culminate in the saturation of M(B) at 3 T. The magnetic structures of SSL systems reflect the frustration of short-ranged magnetic interactions, and in Yb 2 Pt 2 Pb, where the Yb moments are large and classical with strong Ising anisotropy that confines * maronson@bnl.gov them to the SSL plane, we can expect AF states that are analogous to but distinct from those found in SrCu 2 (BO 3 ) 2 at high fields, where Heisenberg quantum spins S = 1/2 are aligned perpendicular to the SSL layers.…”

“…The formation of the antiferromagnetically ordered state in these sublattices destroys the Shastry-Sutherland lattice that was suggested on the basis of the crystal structure in the ab plane [17][18][19][20]33]. Figures 3(c) and 3(d) show that each sublattice is a square lattice of dimers with parallel moments that are all Yb1 or all Yb2 type within a given plane, and that these dimers are stacked antiferromagnetically along the c axis into ladders with alternating Yb1-Yb2 rungs.…”

“…While we do not mean to imply there is a formal correspondence between the magnetic structures in high field SrCu 2 (BO 3 ) 2 and Yb 2 Pt 2 Pb in zero field, we find a much larger separation between the moment-bearing stripes in metallic Yb 2 Pt 2 Pb, suggesting that here the frustration may be embodied in the long-ranged dipole interactions on the SSL lattice, as well as the Ruderman-Kittel-Kasuya-Yosida interactions, mediated by the conduction electrons. The low fields required for the suppression of AF order, for the cascade of magnetization steps that suggest intermediate structures of magnetic and nonmagnetic dimers [19,20], and for the saturation of the individual sublattices in Yb 2 Pt 2 Pb may permit future investigations of the intermediate field states using neutron scattering, currently impossible in SrCu 2 (BO 3 ) 2 where fields approaching 30 T are required to drive analogous modulated phases [10][11][12].…”

Low Temperature Magnetization of Yb2Pt2Pb with the Shastry–Sutherland Type Lattice and a High-Rank Multipole Interaction

“…Similar phase diagram for H k ½100 has also been obtained from the electrical resistivity (T > 0:1 K) and MðHÞ (T > 0:5 K) measurements. 4) The overall features of the phase diagram for H k ½100 are very similar to that for an ordinary antiferromagnet showing a spin flop transition.…”