Magnetic short- and long-range order inPbFe0.5Ta0.5O3

Abstract

PbFe 1/2 Ta 1/2 O3 belongs to the family of PbB x B 1−x O3 which have inherent chemical disorder at the B-site. Due to this disorder, a complex magnetic phase diagram is expected in the material. In this paper, we report experimental results of magnetic properties of PFT through macroscopic characterization, neutron scattering and Mössbauer spectroscopy techniques. With these results we show for the first time that PbFe 1/2 Ta 1/2 O3 behaves very similar to PbFe 1/2 Nb 1/2 O3 , i.e, it undergoes AF transition at 153 K and has a spinglass transition at 10 K, below which the antiferromagnetism coexists with spinglass. We suggest that the mechanism which is responsible for such a non-trivial ground state can be explained by a speromagnet-like spin arrangement similar to the one proposed for PbFe 1/2 Nb 1/2 O3 .

Elastic and anelastic relaxation behaviour of perovskite multiferroics II: PbZr0.53Ti0.47O3 (PZT)–PbFe0.5Ta0.5O3 (PFT)

“…Reported values of the Néel temperature, T N , are generally between ~120 and 180 K [28, 31, 34, 35, 40, 47–49]. Variations between 160 and 230 K can be induced by varying the annealing temperature used during synthesis [42].…”

“…There seems to be acceptance that additional magnetic anomalies below ~ 10–15 K are due to spin glass behaviour [28, 35, 48, 49, 51–53]. A difference from PFN is that, consistent with the calculation of a possible second Néel point at 48 K by Lampis et al [52], Martinez et al [40] proposed another magnetic transition at ~55 K in PFT to account for an anomaly in the temperature dependence of the magnetisation observed in both field-cooled and zero field-cooled measurements.…”

“…A difference from PFN is that, consistent with the calculation of a possible second Néel point at 48 K by Lampis et al [52], Martinez et al [40] proposed another magnetic transition at ~55 K in PFT to account for an anomaly in the temperature dependence of the magnetisation observed in both field-cooled and zero field-cooled measurements. Chillal et al [49] suggested that some canting of Fe moments occurs below ~50 K. The sample described by Martinez et al [36, 40] not only displayed a well-defined magnetic hysteresis loop at room temperature but also contained pyrochlore as an impurity phase.…”

Characterization of multiferroic PbFe0.5Nb0.5O3 and PbFe0.5Ta0.5O3 ceramics derived from citrate polymeric precursors

“…Lead iron niobate PbFe 0.5 Nb 0.5 O 3 (PFN) and lead iron tantalate PbFe 0.5 Ta 0.5 O 3 (PFT), of the perovskite structure, belong to such compounds . They exhibit chemical disorder in the Fe 3+ /Nb 5+ or Fe 3+ /Ta 5+ ion sublattices and consequently a frustration in the magnetic subsystem as well as a relaxor or diffuse ferroelectric phase transition nature . For both the relaxor and the diffuse phase transition natures, the real part of electric permittivity in function of temperature ε ’( T ) exhibits a broad diffuse maximum.…”

“…Due to very close lattice parameters and the same iron populations, the Fe 3+ ions create nearly identical magnetic subsystems in PbFe 0.5 Nb 0.5 O 3 and PbFe 0.5 Ta 0.5 O 3 , which undergo the same sequence of two magnetic transitions from the paramagnetic phase to the antiferromagnetic (AFM) one at Neel temperature T N ≈ 150 K and then to the spin‐glass (SG) state at approximately 10 K . There are two models of the SG and AFM states coexistence below 10 K proposed.…”