Fig. 1 The crystal structure of Cu2OCl2. Green, yellow, and blue atoms denote Cu, Cl, and O ions, respectively. The structure consists of CuO2Cl2 square chains running in the [1 1 0] and [±1 ∓1 0] directions (left). The squares are the basal planes of strongly distorted CuO2Cl4 octahedra (green) with apical Cl ions that are farther away from the Cu ions (middle). Alternatively, the structure can be described as a network of OCu4 tetrahedra (right).
Fig. 3 Evidence of multiferroicity in Cu2OCl2. (A to D) Dielectric constant ε(T) and dielectric loss tanδ(T) of Cu2OCl2 single crystals measured in the c direction at different frequencies in zero field and also at 9 T. (E) The temperature dependence of the zero-field electric polarization in Cu2OCl2, measured with applied positive and negative poling electric fields. The dotted curves are the corresponding values for a polycrystalline (pellet) sample. (F) The coefficient (ε(H) − ε(H = 0))/ε(H = 0) as a function of magnetic field shows the magnetodielectric effect in Cu2OCl2 for different temperatures (measured with 10 kHz).
Fig. 4 Incommensurate magnetic structure of Cu2OCl2. Powder neutron diffraction measurements of Cu2OCl2. Below TN, three magnetic peaks appear (magenta arrows). The red line represents the refinement with a spin structure according to the irreducible representation Irep2. The right bottom panel depicts the spin structure. For clarity, we show the corresponding OCu4 tetrahedral chains (orange) in the upper right panel. Within each OCu4 tetrahedral chain, the magnetic moments point in the chain direction. a.u., arbitrary units.
Supplementary Materials
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/5/e1600353/DC1
Powder x-ray diffraction
Magnetization measurements
Single crystal x-ray diffraction
Pyroelectric coefficient measurements
fig. S1. Powder x-ray diffraction pattern of Cu2OCl2.
fig. S2. Magnetic susceptibility of our polycrystalline Cu2OCl2 samples.
fig. S3. First temperature derivative of the magnetic susceptibility of Cu2OCl2 single crystals indicating TN.
fig. S4. Specific heat of a Cu2OCl2 single crystal indicating a value of TN that is consistent with our magnetization.
CIF-file: Cu2OCL2_Fddd_v3_s.cif
Additional Files
Supplementary Materials
This PDF file includes:
- Powder x-ray diffraction
- Magnetization measurements
- Single crystal x-ray diffraction
- Pyroelectric coefficient measurements
- fig. S1. Powder x-ray diffraction pattern of Cu2OCl2.
- fig. S2. Magnetic susceptibility of our polycrystalline Cu2OCl2 samples.
- fig. S3. First temperature derivative of the magnetic susceptibility of Cu2OCl2 single crystals indicating TN.
- fig. S4. Specific heat of a Cu2OCl2 single crystal indicating a value of TN that is consistent with our magnetization.
Other Supplementary Material for this manuscript includes the following:
- CIF-file: Cu2OCL2_Fddd_v3_s.cif
Files in this Data Supplement:
