EXAFS evidence for the spin–phonon coupling in the monoclinic PrNiO<sub>3</sub> nickelate perovskite

Rodrigues, João Elias Figueiredo Soares; Rosa, Angelika Dorothea; López-Sánchez, Jesús; Sebastiani-Tofano, E.; Nemes, N. M.; Martinez, J.L.; Alonso, J. A.; Mathon, O.

doi:10.1039/d2tc03063b

Cited by 4 publications

(18 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In Figure b, the drop of the Debye–Waller exponent at 10.8 GPa of the parallel MSRDs of pair-bonds Ni–O corroborates the above statement. A hybridization between Ni 3d and O 2p orbitals is expected to follow the IMT in nickelates, which promotes the bandgap closing and could explain the drop of the Debye–Waller exponent from sub-region I to II. , At region II, the most likely hypothesis is that a collective interaction takes place because of the strong hybridization of the single electron Ni e g and O 2p that leads to a bandwidth enhancement in the metallic state. Once the metallic state is stabilized, the crystal structure can be compressed again at 25.4 GPa.…”

Section: Resultsmentioning

confidence: 99%

“…This reliable model of Ni–O distances with two sets of averaged bond distances, which will be referred to as Ni–O 1a and Ni–O 2a (“a” means “average”), was built by (1) averaging the 8-long Ni–O distances with d 1 ≥ 1.955 Å and (2) averaging the remaining Ni–O paths with d 2 < 1.95 Å, which are the 4-short Ni2–O 1,3 (see the sketch of the local environment of [Ni1,2O 6 ] units in Figure S3). The same model was recently applied for EXAFS modeling in PrNiO 3 . The correct weighting of path contributions during fitting was set to the CN of 4 and 2 for Ni–O 1a and Ni–O 2a , respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The cationic Ni–Ni pair unit accounts for the feature at ∼3.6 Å. Because our EXAFS input model is an approximate solution for describing the short-range structure of the TlNiO 3 nickelate in the entire pressure range, we expect that associated errors with this assumption will be manifested through the Debye–Waller exponent [σ || 2 or ⟨ u || 2 ⟩] of all the scattering paths.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Evidence for a Pressure-Induced Phase Transition in the Highly Distorted TlNiO₃ Nickelate

et al. 2023

Self Cite

View full text Add to dashboard Cite

Rare-earth perovskite nickelates RNiO 3 (R stands for Y, rare earths, Tl or Bi) have attracted wide attention in the past few decades because of their unique electronic properties that emerge from the insulator−metal transition (IMT). This transition can be tuned by chemical substitutions or by external variables, like pressure and temperature, but the mechanism of this transition still remains debated. While most previous studies focused on nickelates with partially filled 4f cations on the R site, here we studied the mechanism of the pressure-induced phase transition on a rare Tl 3+ nickelate, which comprises fully filled 4f orbitals. We probed the pressure-induced structural and electronic changes taking place at the bulk, medium, and local atomic level at room temperature by using synchrotron X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) as probing techniques, respectively. High-resolution XRD data under ambient conditions show evidence for the monoclinic phase of TlNiO 3 , as characterized by the charge ordering between Ni 3−δ and Ni 3+δ in the insulator regime. High-pressure XRD data elucidated an anomaly in the evolution of the lattice parameters at 10.8 GPa, which we assigned to the structural transition P2 1 /n → Pbnm. High-pressure EXAFS data at the Ni K-edge provide a solid proof for a short-order charge disproportionation under near ambient conditions. The Ni−O pair-bond compression curves unveiled an isotropic overlapping Ni t 2g 6 e g 1 → O 2p, with an anomaly at 10.8 GPa. The pressure evolution of the bond-distance variance (Debye−Waller exponents) lodged a hardening at this pressure point, suggesting constrained atomic displacements in the average range of ±0.04(5) Å. We propose that this reduced motional freedom could be linked to an electron−phonon coupling, which is the driving force behind the mechanisms of the IMT. We demonstrated that the XANES technique can be applied to ascertain the pressure-induced transition, by tracking the anomalous behavior of the position and width (full width at half-maximum) of the XANES features.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Evidence for a Pressure-Induced Phase Transition in the Highly Distorted TlNiO₃ Nickelate

et al. 2023

Self Cite

View full text Add to dashboard Cite

show abstract

“…Recent literature suggests that the IMT in nickelates has different mechanisms for R = Pr, Nd (medium size) and R = Lu, Tl, Y, Sm (small size). ,, It remains under debate to what extent structural, vibrational, electronic, and magnetic degrees of freedom influence this transition and how their involvements change for distinct rare earth elements. For small R cation size nickelates, it has been proposed that an intermediate paramagnetic insulator phase occurs during the IMT due to the band gap opening .…”

Section: Discussionmentioning

confidence: 99%

Mapping Pressure- and Temperature-Induced Structural and Magnetic Transitions in Perovskite PrNiO₃ with Local and Long-Range Probes

Rodrigues,

Rosa,

Gainza

et al. 2023

Chem. Mater.

Self Cite

View full text Add to dashboard Cite

The RNiO 3 nickelate perovskites represent a promising class of materials for spintronics applications such as in modern communication devices. This is related to the large diversity of properties shown by these compounds. Indeed, depending on the external parameters, such as temperature, pressure, or R cation size, they can exhibit para-or antiferromagnetic behavior and can transform from an insulator to a metal. Among them, PrNiO 3 is one of the most important members because it exhibits tunable electronic and magnetic properties. However, our understanding of how these properties can be modified through external parameters, such as pressure and temperature, remains under debate. In this work, we characterized the structural, electronic, and magnetic properties of PrNiO 3 in the range of 0−21 GPa and 10−973 K. For this purpose, we performed synchrotron X-ray diffraction (SXRD), X-ray absorption nearedge structure spectroscopy (XANES), and magnetic measurements. We compared the experimental XANES data with ab initio calculations to extract information about the electronic structure. The diffraction data demonstrated a sharp transition at the bulk level between monoclinic and orthorhombic PrNiO 3 (P2 1 /n → Pbnm) at T IM ∼ 130 K, while XANES data, which probe the medium-range and electronic structure, showed progressive changes between 90 and 130 K. The latter is in accordance with our previous EXAFS data, attesting that this transition occurs around 130 K and that it is driven at the local and medium-range scales. Between 700 and 800 K at ambient pressure, the Pbnm phase transforms into a rhombohedral phase (R3̅ c), in agreement with a previous laboratory X-ray diffraction study. Our XANES data and ab initio simulations across this transition indicate a significant raising of the orbital overlap between Ni 3d and O 2p, suggesting superior electronic properties of the rhombohedral phase compared to the orthorhombic structure. Under isothermal cold compression, we found that the Pbnm to R3̅ c transition is characterized by a large coexisting domain between 5.8 and 12.2 GPa. Based on the present and literature data, we proposed an extended pressure-and temperature-phase diagram of PrNiO 3 and provided first-order constraints on the interplay between external parameters and properties in nickelates.

show abstract

“…Similarly, no anomalies were detected for the Debye−Waller exponent (σ Γ 2 ) along the entire probed temperature range that would characterize an emergence of the spin−phonon coupling, in analogy to our recent report on PrNiO 3 nickelate. 39 Most likely, the structural differences between the intercalation sulfide and the perovskite oxide may explain the absence of spin−phonon coupling in the former one. The former material has a layered structure, and the iron FeS 6 octahedral units are less connected to their neighbors when compared to the perovskite oxide.…”

Section: Local Atomic Structurementioning

confidence: 99%

Elucidating the Magnetoelastic Coupling, Pressure-Dependent Magnetic Behavior, and Anomalous Hall Effect in Fe_xTi₂S₄ Intercalation Sulfides

Silva,

Rodrigues,

Rosa

et al. 2023

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

Transition-metal chalcogenides with intercalated layered structures are interesting systems in material physics due to their attractive electronic and magnetic properties, with applications in the fields of magnetic refrigerators, catalysts, and thermoelectrics, among others. In this work, we studied in detail the structural, electronic, and magnetic properties of (Fe,Ti)-based sulfides with formula Fe x Ti2S4 (x = 0.24, 0.32, and 0.42), prepared as polycrystalline materials under high-pressure conditions. They present a layered Heideite-type crystal structure, as assessed by synchrotron X-ray diffraction. A local structure analysis using Fe K-edge extended X-ray-absorption fine structure (EXAFS) data unveiled a conspicuous contraction of the main Fe–S bond in Fe0.24Ti2S4 at the vicinity of the magnetic transition 60–80 K. We suggest that this anomaly is related to magnetoelastic coupling effects. The EXAFS analysis allowed extraction of the Einstein temperatures (θ E ), i.e., the phonon contribution to the specific heat, for the two bond pairs Fe–S(1) [θ E ≈318 K; 290 K (C/T)] and Fe–Ti(1) [θ E ≈218 K; 190 K (C/T)]. In addition to the structural and local vibrational measurements, we probed the magnetic properties using magneto-calorimetry, magnetometry under applied pressure, magnetoresistance (MR), and Hall effect measurements. We observed the appearance of a broad peak in the specific heat around 120 K in the x = 0.42 compound that we associated with an antiferromagnetic ordering electronic transition. We found that the antiferromagnetic transition temperature is pressure and composition sensitive and reduces at 1.2 GPa by ∼12 and ∼3 K, for the members with x = 0.24 and x = 0.42, respectively. Similarly, the saturation magnetization in the ordered phase depends on both pressure and iron content, reducing its value by 50, 90, and 30% for x = 0.24, 0.32, and 0.42, respectively. We observed clear jumps in the magnetic hysteresis loops, MR, and anomalous Hall effect (AHE) below 2 K at fields around 2–4 T. We associated this observation with the metamagnetic transitions; from the Berry-curvature a decoupling parameter of S H = 0.12 V–1 is determined. Comparison of the results on the temperature-dependent magnetization, MR, and AHE elucidates a strong inelastic scattering contribution to the AHE at higher temperatures due to the cluster spin-glass phase.

show abstract

EXAFS evidence for the spin–phonon coupling in the monoclinic PrNiO₃ nickelate perovskite

Abstract: An understanding of the electronic and structural changes across the temperature-induced phase transition in nickelates with perovskite structure (RNiO3, with R being Y, Tl, lanthanides) is of key importance to...

Cited by 4 publications

References 47 publications

Evidence for a Pressure-Induced Phase Transition in the Highly Distorted TlNiO₃ Nickelate

Evidence for a Pressure-Induced Phase Transition in the Highly Distorted TlNiO₃ Nickelate

Mapping Pressure- and Temperature-Induced Structural and Magnetic Transitions in Perovskite PrNiO₃ with Local and Long-Range Probes

Elucidating the Magnetoelastic Coupling, Pressure-Dependent Magnetic Behavior, and Anomalous Hall Effect in Fe_xTi₂S₄ Intercalation Sulfides

Contact Info

Product

Resources

About

EXAFS evidence for the spin–phonon coupling in the monoclinic PrNiO3 nickelate perovskite

Abstract: An understanding of the electronic and structural changes across the temperature-induced phase transition in nickelates with perovskite structure (RNiO3, with R being Y, Tl, lanthanides) is of key importance to...

Cited by 4 publications

References 47 publications

Evidence for a Pressure-Induced Phase Transition in the Highly Distorted TlNiO3 Nickelate

Evidence for a Pressure-Induced Phase Transition in the Highly Distorted TlNiO3 Nickelate

Mapping Pressure- and Temperature-Induced Structural and Magnetic Transitions in Perovskite PrNiO3 with Local and Long-Range Probes

Elucidating the Magnetoelastic Coupling, Pressure-Dependent Magnetic Behavior, and Anomalous Hall Effect in FexTi2S4 Intercalation Sulfides

Contact Info

Product

Resources

About

EXAFS evidence for the spin–phonon coupling in the monoclinic PrNiO₃ nickelate perovskite

Evidence for a Pressure-Induced Phase Transition in the Highly Distorted TlNiO₃ Nickelate

Evidence for a Pressure-Induced Phase Transition in the Highly Distorted TlNiO₃ Nickelate

Mapping Pressure- and Temperature-Induced Structural and Magnetic Transitions in Perovskite PrNiO₃ with Local and Long-Range Probes

Elucidating the Magnetoelastic Coupling, Pressure-Dependent Magnetic Behavior, and Anomalous Hall Effect in Fe_xTi₂S₄ Intercalation Sulfides