Erratum to: npj Quantum Materials (2017); doi:10.1038/s41535-017-0009-8; Published 08 February 2017
This paper contained an incorrect grant code in the Acknowledgements section. This has now been replaced with the correct code.
This error has now been corrected in the HTML and PDF versions of this article.
The online version of the original article can be found at https://doi.org/10.1038/s41535-017-0009-8.