1
|
Banerjee S, Gürsoy D, Deng J, Kahnt M, Kramer M, Lynn M, Haskel D, Strempfer J. 3D imaging of magnetic domains in Nd 2Fe 14B using scanning hard X-ray nanotomography. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:877-887. [PMID: 38771778 PMCID: PMC11226165 DOI: 10.1107/s1600577524003217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 04/15/2024] [Indexed: 05/23/2024]
Abstract
Nanoscale structural and electronic heterogeneities are prevalent in condensed matter physics. Investigating these heterogeneities in 3D has become an important task for understanding material properties. To provide a tool to unravel the connection between nanoscale heterogeneity and macroscopic emergent properties in magnetic materials, scanning transmission X-ray microscopy (STXM) is combined with X-ray magnetic circular dichroism. A vector tomography algorithm has been developed to reconstruct the full 3D magnetic vector field without any prior noise assumptions or knowledge about the sample. Two tomographic scans around the vertical axis are acquired on single-crystalline Nd2Fe14B pillars tilted at two different angles, with 2D STXM projections recorded using a focused 120 nm X-ray beam with left and right circular polarization. Image alignment and iterative registration have been implemented based on the 2D STXM projections for the two tilts. Dichroic projections obtained from difference images are used for the tomographic reconstruction to obtain the 3D magnetization distribution at the nanoscale.
Collapse
Affiliation(s)
| | - Doğa Gürsoy
- X-ray Science DivisionArgonne National LaboratoryLemontIL60439USA
| | - Junjing Deng
- X-ray Science DivisionArgonne National LaboratoryLemontIL60439USA
| | - Maik Kahnt
- MAX IV LaboratoryLund University22100LundSweden
| | | | | | - Daniel Haskel
- X-ray Science DivisionArgonne National LaboratoryLemontIL60439USA
| | - Jörg Strempfer
- X-ray Science DivisionArgonne National LaboratoryLemontIL60439USA
| |
Collapse
|
2
|
Girardi D, Finizio S, Donnelly C, Rubini G, Mayr S, Levati V, Cuccurullo S, Maspero F, Raabe J, Petti D, Albisetti E. Three-dimensional spin-wave dynamics, localization and interference in a synthetic antiferromagnet. Nat Commun 2024; 15:3057. [PMID: 38594233 PMCID: PMC11004151 DOI: 10.1038/s41467-024-47339-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 03/28/2024] [Indexed: 04/11/2024] Open
Abstract
Spin waves are collective perturbations in the orientation of the magnetic moments in magnetically ordered materials. Their rich phenomenology is intrinsically three-dimensional; however, the three-dimensional imaging of spin waves has so far not been possible. Here, we image the three-dimensional dynamics of spin waves excited in a synthetic antiferromagnet, with nanoscale spatial resolution and sub-ns temporal resolution, using time-resolved magnetic laminography. In this way, we map the distribution of the spin-wave modes throughout the volume of the structure, revealing unexpected depth-dependent profiles originating from the interlayer dipolar interaction. We experimentally demonstrate the existence of complex three-dimensional interference patterns and analyze them via micromagnetic modelling. We find that these patterns are generated by the superposition of spin waves with non-uniform amplitude profiles, and that their features can be controlled by tuning the composition and structure of the magnetic system. Our results open unforeseen possibilities for the study and manipulation of complex spin-wave modes within nanostructures and magnonic devices.
Collapse
Affiliation(s)
- Davide Girardi
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Simone Finizio
- Swiss Light Source, Paul Scherrer Institut; Forschungsstrasse 111 5232 PSI, Villigen, Switzerland
| | - Claire Donnelly
- Max Planck Institute for Chemical Physics of Solids; Nöthnitzer Str. 40, 01187, Dresden, Germany
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2), Hiroshima University, Hiroshima, 739-8526, Japan
| | - Guglielmo Rubini
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Sina Mayr
- Swiss Light Source, Paul Scherrer Institut; Forschungsstrasse 111 5232 PSI, Villigen, Switzerland
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
| | - Valerio Levati
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Simone Cuccurullo
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Federico Maspero
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Jörg Raabe
- Swiss Light Source, Paul Scherrer Institut; Forschungsstrasse 111 5232 PSI, Villigen, Switzerland
| | - Daniela Petti
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy.
| | - Edoardo Albisetti
- Dipartimento di Fisica, Politecnico di Milano; Piazza Leonardo da Vinci 32, Milano, 20133, Italy.
| |
Collapse
|
3
|
Butcher TA, Phillips NW, Chiu CC, Wei CC, Ho SZ, Chen YC, Fröjdh E, Baruffaldi F, Carulla M, Zhang J, Bergamaschi A, Vaz CAF, Kleibert A, Finizio S, Yang JC, Huang SW, Raabe J. Ptychographic Nanoscale Imaging of the Magnetoelectric Coupling in Freestanding BiFeO 3. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2311157. [PMID: 38402421 DOI: 10.1002/adma.202311157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/23/2023] [Indexed: 02/26/2024]
Abstract
Understanding the magnetic and ferroelectric ordering of magnetoelectric multiferroic materials at the nanoscale necessitates a versatile imaging method with high spatial resolution. Here, soft X-ray ptychography is employed to simultaneously image the ferroelectric and antiferromagnetic domains in an 80 nm thin freestanding film of the room-temperature multiferroic BiFeO3 (BFO). The antiferromagnetic spin cycloid of period 64 nm is resolved by reconstructing the corresponding resonant elastic X-ray scattering in real space and visualized together with mosaic-like ferroelectric domains in a linear dichroic contrast image at the Fe L3 edge. The measurements reveal a near perfect coupling between the antiferromagnetic and ferroelectric ordering by which the propagation direction of the spin cycloid is locked orthogonally to the ferroelectric polarization. In addition, the study evinces both a preference for in-plane propagation of the spin cycloid and changes of the ferroelectric polarization by 71° between multiferroic domains in the epitaxial strain-free, freestanding BFO film. The results provide a direct visualization of the strong magnetoelectric coupling in BFO and of its fine multiferroic domain structure, emphasizing the potential of ptychographic imaging for the study of multiferroics and non-collinear magnetic materials with soft X-rays.
Collapse
Affiliation(s)
- Tim A Butcher
- Paul Scherrer Institut, Villigen PSI, 5232, Switzerland
| | | | - Chun-Chien Chiu
- Department of Physics, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Chia-Chun Wei
- Department of Physics, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Sheng-Zhu Ho
- Department of Physics, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Yi-Chun Chen
- Department of Physics, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Erik Fröjdh
- Paul Scherrer Institut, Villigen PSI, 5232, Switzerland
| | | | - Maria Carulla
- Paul Scherrer Institut, Villigen PSI, 5232, Switzerland
| | - Jiaguo Zhang
- Paul Scherrer Institut, Villigen PSI, 5232, Switzerland
| | | | | | | | | | - Jan-Chi Yang
- Department of Physics, National Cheng Kung University, Tainan, 70101, Taiwan
- Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, Tainan, 70101, Taiwan
| | | | - Jörg Raabe
- Paul Scherrer Institut, Villigen PSI, 5232, Switzerland
| |
Collapse
|
4
|
Finizio S, Bailey JB, Olsthoorn B, Raabe J. Periodogram-Based Detection of Unknown Frequencies in Time-Resolved Scanning Transmission X-ray Microscopy. ACS NANO 2022; 16:21071-21078. [PMID: 36512505 DOI: 10.1021/acsnano.2c08874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Pump-probe time-resolved imaging is a powerful technique that enables the investigation of dynamical processes. Signal-to-noise and sampling rate restrictions normally require that cycles of an excitation are repeated many times with the final signal reconstructed using a reference. However, this approach imposes restrictions on the types of dynamical processes that can be measured, namely, that they are phase locked to a known external signal (e.g., a driven oscillation or impulse). This rules out many interesting processes such as auto-oscillations and spontaneously forming populations, e.g., condensates. In this work we present a method for time-resolved imaging, based on the Schuster periodogram, that allows for the reconstruction of dynamical processes where the intrinsic frequency is not known. In our case we use time of arrival detection of X-ray photons to reconstruct magnetic dynamics without using a priori information on the dynamical frequency. This proof-of-principle demonstration will allow for the extension of pump-probe time-resolved imaging to the important class of processes where the dynamics are not locked to a known external signal and in its presented formulation can be readily adopted for X-ray imaging and also adapted for wider use.
Collapse
Affiliation(s)
| | - Joe Bilko Bailey
- Paul Scherrer Institut, 5232Villigen PSI, Switzerland
- Institut de Physique, EPFL, 1015Lausanne, Switzerland
| | - Bart Olsthoorn
- Nordita, KTH Royal Institute of Technology and Stockholm University, Hannes Alfvéns väg 12, SE-106 91Stockholm, Sweden
| | - Jörg Raabe
- Paul Scherrer Institut, 5232Villigen PSI, Switzerland
| |
Collapse
|
5
|
TimeMaxyne: A Shot-Noise Limited, Time-Resolved Pump-and-Probe Acquisition System Capable of 50 GHz Frequencies for Synchrotron-Based X-ray Microscopy. CRYSTALS 2022. [DOI: 10.3390/cryst12081029] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
With the advent of modern synchrotron sources, X-ray microscopy was developed as a vigorous tool for imaging material structures with element-specific, structural, chemical and magnetic sensitivity at resolutions down to 25 nm and below. Moreover, the X-ray time structure emitted from the synchrotron source (short bunches of less than 100 ps width) provides a unique possibility to combine high spatial resolution with high temporal resolution for periodic processes by means of pump-and-probe measurements. To that end, TimeMaxyne was developed as a time-resolved acquisition setup for the scanning X-ray microscope MAXYMUS at the BESSY II synchrotron in order to perform high precision, high throughput pump-and-probe imaging. The setup combines a highly sensitive single photon detector, a real time photon sorting system and a dedicated synchronization scheme for aligning various types of sample excitations of up to 50 GHz bandwidth to the photon probe. Hence, TimeMaxyne has been demonstrated to be capable of shot-noise limited, time-resolved imaging, at time resolutions of 50 ps and below, only limited by the X-ray pulse widths of the synchrotron.
Collapse
|