Abstract text (incl. figure legends and references)

1. Introduction
More than a decade has passed since the first experimental evidence of magnetic Bloch-type skyrmions in MnSi [1]. Since then, driven by their high potential for applications in future magnetic memory devices, skyrmions and related magnetic nano-objects of non-trivial topology have been in the focus of intensive research in the scientific community, and many novel spin textures have been discovered. In the course of these efforts, antiskyrmions (aSks) were recently observed in the tetragonal Heusler material Mn_1.4PtSn by Lorentz Transmission Electron Microscopy (LTEM). Beyond that, the material is known to host a wide range of other magnetic structures such as non-topological (NT) bubbles, elliptical skyrmions and spin helices [3].

2. Objectives
In order to better understand the formation of aSks we have conducted complementary experiments of resonant elastic x-ray scattering (REXS) and LTEM on an identical lamella of Mn_1.4PtSn. REXS enables us to directly measure the orientation and magnitude of the spin propagation vectors of the various magnetic phases occurring in Mn_1.4PtSn. While REXS provides for diffraction patterns, LTEM allows to directly image and identify the underlying magnetric structures and to navigate the material"s complex phase diagram, which depends not only on temperature and sample shape, but also on strength and orientation of an external magnetic field as well as on the history of its application.

3. Materials & methods
We use high quality single crystals of Mn_1.4PtSn grown by self-flux method for our experiments. In order to realize complementary measurements on identical samples, thin lamellas were cut by FIB-Milling and placed on specifically designed molybdenum-discs (d=3 mm) fitting to commercially available TEM holders. Custom-designed sample hoilders haver been developed to ensure compatibility with the REXS setup. The REXS experiments were carried out at the I10 end station at the Diamond Lightsource (UK). The experimental setup was equipped with an octupole vector magnet, which allowed to explore the highly complex magnetic phase diagram of Mn_1.4PtSn by offering 360° of freedom in magnetic field direction and fields of up to 600 mT.

4. Results
Our complementary approach allows us to unambiguously link the helical phase, NT bubble and aSks phase in Mn_1.4PtSn as identified from LTEM measurements to the REXS scattering patterns we measured on the identical sample (Fig 1). In combination with the quantitative analysis of the REXS pattern the study provides new insights into the various (field-induced) magnetic phase transitions in the materials.

5. Conclusion
Along this approach, the intimate correlation of LTEM and REXS experiments conducted on identical samples has proven an ideal tool to not only doubtlessly identify individual phases but also to navigate the high-dimensional parameter space and characterize the nature of the occurring phase transition in great detail.

Acknowledgement(s):

This study was supported by the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM) and by the DFG through SPP 2137.

Reference(s):

[1] S. Mühlbauer et al., Science. 323, 915-919 (2009).

[2] A.K. Nayak et al., Nature. 548, 561 (2017).

[3] L. Peng et al., Nature Nanotechnol. 15, 181-186 (2020).