Abstract
We present an extensive study on the effect of substrate orientation, strain, stoichiometry, and defects on spin-ice physics in Ho2Ti2O7 thin films grown onto yttria-stabilized-zirconia substrates. We find that growth in different orientations produces different strain states in the films. All films exhibit similar c-axis lattice parameters for their relaxed portions, which are consistently larger than the bulk value of 10.1 Å. Transmission electron microscopy reveals antisite disorder and growth defects to be present in the films, but evidence of stuffing is not observed. The amount of disorder depends on the growth orientation, with the (110) film showing the least. Magnetization measurements at 1.8 K show the expected magnetic anisotropy and saturation magnetization values associated with a spin ice for all orientations; shape anisotropy is apparent when comparing in- and out-of-plane directions. Significantly, only the (110)-oriented films display the hallmark spin-ice plateau state in magnetization, albeit less well defined compared to the plateau observed in a single crystal. Neutron-scattering maps on the more disordered (111)-oriented films show the Q = 0 phase previously observed in bulk materials, but the Q = X phase giving the plateau state remains elusive. We conclude that the spin-ice physics in thin films is modified by defects and strain, leading to a reduction in the temperature at which correlations drive the system into the spin-ice state.
| Original language | English |
|---|---|
| Article number | 084412 |
| Journal | Physical Review Materials |
| Volume | 3 |
| Issue number | 8 |
| DOIs | |
| State | Published - Aug 16 2019 |
| Externally published | Yes |
Funding
C.B. acknowledges support from the National Research Foundation, under Grant No. NSF DMR-1847887. J.N., C.C., and T.S. acknowledge support from the National Research Foundation, under Grant No. NSF DMR-1606952. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement No. DMR-1644779, and the State of Florida. H.D.Z. acknowledges support from the NHMFL Visiting Scientist Program, which is supported by NSF Cooperative Agreement No. DMR-1157490 and the State of Florida. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF), supported by the National Science Foundation under Award No. ECCS-1542152. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Access to MACS was provided by the Center for High Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement No. DMR-1508249. C.B. acknowledges support from the National Research Foundation, under Grant No. NSF DMR-1847887. J.N., C.C., and T.S. acknowledge support from the National Research Foundation, under Grant No. NSF DMR-1606952. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement No. DMR-1644779, and the State of Florida. H.D.Z. acknowledges support from the NHMFL Visiting Scientist Program, which is supported by NSF Cooperative Agreement No. DMR-1157490 and the State of Florida. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF), supported by the National Science Foundation under Award No. ECCS-1542152. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Access to MACS was provided by the Center for High Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement No. DMR-1508249.
| Funders | Funder number |
|---|---|
| National Research Foundation | |
| Office of Basic Energy Sciences | |
| State of Florida | ECCS-1542152, DMR-1157490 |
| National Science Foundation | DMR-1644779, DMR-1847887, 1157490, 1542152, 1508249, DMR-1606952 |
| U.S. Department of Energy | |
| National Institute of Standards and Technology | DMR-1508249 |
| Office of Science | |
| Basic Energy Sciences | DE-AC02-76SF00515 |
| National Research Foundation of Korea |