Fabrication of optical magnetic mirrors using bent and mushroom-like carbon nanotubes Habib Rostami, Yaser Abdi, Ezatollah Arzi * Nanophysics Research Laboratory, Department of Physics, University of Tehran, Tehran, Iran ARTICLE INFO Article history: Received 20 January 2010 Accepted 24 May 2010 Available online 27 May 2010 ABSTRACT Fabrication of an optical magnetic mirror using carbon nanotube-based 3-dimensional nano-structures is reported. Carbon nanostructures were grown in a plasma enhanced chemical vapor deposition reactor on Ni catalyst islands using a mixture of C 2 H 2 and H 2 gases. Bent carbon nanotubes (CNTs) with a controllable bending angle were obtained by changing the direction of the electrical field of the applied plasma. Mushroom-like carbon nanostructures with a high-impedance surface were obtained by deposition of a gold layer on vertically grown CNTs using a sputtering system. Phase shift measurements of the fab- ricated nanostructured surfaces were carried out by an interferometer setup. Phase differ- ences between the incident beam on the as-prepared surfaces and the reflected beam from them were found to be almost zero, indicating that the direction of the electric field had not been changed upon reflection. Scanning electron microscopy and atomic force microscopy were used for morphological study of the prepared samples. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction It has been shown that metallic nanostructures with a feature size of smaller or comparable with the wavelength of the light incident on them have unique and fascinating optical proper- ties [1]. Manipulation of optical properties, to suit different applications of interest, is not only achieved by changing a material’s chemical composition but also obtained by chang- ing the structural parameters such as grain size and shape [2–4]. Recently a technique has been introduced to fabricate a structured metallic surface – called magnetic mirror or mag- netic wall – with novel properties [5–7]. The optical magnetic mirror is similar to high-impedance surface that imposes ex- tremely unusual electromagnetic boundary conditions in such a way that does not change the phase of the electric field upon reflection, but instead reverses the direction of the mag- netic field [5,8]. This property is different from a dielectric interface or metallic mirror, which reverses the electric field of the reflected wave (see Fig. 1). To have a magnetic mirror in the range of optical waves, one needs to create a sculptured surface with nanoscale pat- terns compatible to the optical wavelength [9]. Apart from this wavelength range, the structure acts as a good broadband metallic reflecting surface. In this paper we have used carbon nanotube (CNT) array to fabricate a nanostructured surface having the above mentioned unusual optical properties. CNTs, due to their unique structure and fascinating elec- tronic properties, have found many applications in electron- ics and optical fields such as the fabrication of interconnects [10], field emission and field effect transistors [11,12], optical antennas [13] and photonic crystals using an array of vertically aligned nanotubes [14]. We have recently reported the fabrication of bent multiwall CNTs by plasma en- hanced chemical vapor deposition (PECVD) and their applica- tion in the fabrication of field ionization gas sensors [15]. Because of their individual optical scattering behavior, the bent metallic CNTs and also Au-coated vertical nanotubes were used to produce optical magnetic mirrors in this paper. 0008-6223/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbon.2010.05.049 * Corresponding author: Fax: +98 21 88004781. E-mail address: arzi@khayam.ut.ac.ir (E. Arzi). CARBON 48 (2010) 3659 – 3666 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/carbon