Charge-driven first-order magnetic transition in NiPS3
Junik Hwang1, Seonghoon Park1, Beom Hyun Kim2
1Department of Physics, Changwon National University, Changwon 51139, Republic of Korea.
Summary
Two-dimensional van der Waals antiferromagnets like NiPS3 exhibit a first-order magnetic transition due to strong charge-spin coupling. This transition, observed via phosphorus-31 nuclear magnetic resonance, shows phase coexistence and a discontinuous order parameter at the Néel temperature.
Area of Science:
- Condensed matter physics
- Materials science
- Quantum magnetism
Background:
- Understanding cross-coupling in fundamental degrees of freedom is crucial in condensed matter physics.
- While studied in 3D materials, the behavior in 2D materials remains largely unexplored.
- Van der Waals materials offer a unique platform to investigate reduced dimensionality effects.
Purpose of the Study:
- To investigate the nature of magnetic phase transitions in two-dimensional (2D) van der Waals materials.
- To explore the role of charge-spin coupling in the magnetic ordering of NiPS3.
- To determine if the magnetic transition in NiPS3 is first-order or second-order.
Main Methods:
- Utilized phosphorus-31 nuclear magnetic resonance (31P NMR) spectroscopy.
- Analyzed NMR spectra across the magnetic ordering temperature (Néel temperature, TN).
- Measured the order parameter and spin fluctuations near TN.
Main Results:
- Identified a first-order magnetic phase transition in the 2D antiferromagnet NiPS3 at TN = 155 K.
- Observed coexistence of paramagnetic and antiferromagnetic phases in a finite temperature range near TN.
- Detected a discontinuity in the order parameter and absence of critical spin fluctuations above TN.
Conclusions:
- The magnetic transition in NiPS3 is definitively first-order, driven by strong charge-spin coupling.
- A proposed mechanism involves a charge stripe instability linked to a Zhang-Rice triplet ground state.
- This finding provides new insights into magnetic phenomena in 2D materials.
Keywords:
Zhang-Rice excitonfirst-order magnetic transitionmagnetic van der Waalsnuclear magnetic resonanceMore Related Videos
08:55High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy
Published on: October 9, 2020
5.5K
08:55Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
8.5K
Related Concept Videos
01:23Atomic Nuclei: Nuclear Relaxation Processes
631
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis.
631
01:14Atomic Nuclei: Nuclear Spin State Population Distribution
953
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
953
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.0K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.0K
01:05Atomic Nuclei: Magnetic Resonance
634
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
634
01:03Atomic Nuclei: Nuclear Spin State Overview
884
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of...
884
00:59Atomic Nuclei: Nuclear Magnetic Moment
1.1K
All atomic nuclei are positively charged. When they have a nonzero spin, they behave like rotating charges. As a consequence of their charge and spin, these nuclei generate a magnetic field (B). This, in turn, gives rise to a magnetic moment (μ), which is randomly oriented in the absence of an external magnetic field. When an external magnetic field (B0) is applied, the magnetic moment vectors can align with the field or against it in 2 + 1 orientations. A hydrogen nucleus, which is just a...
1.1K